Fix configuration negotiation so that existing dependents with config clauses are always considered for negotiation

3 files changed, 1295 insertions, 47 deletions

diff --git a/bpkg/pkg-build-collect.cxx b/bpkg/pkg-build-collect.cxx
index b3b50aa..4db5e7d 100644
--- a/bpkg/pkg-build-collect.cxx
+++ b/bpkg/pkg-build-collect.cxx
@@ -1681,9 +1681,12 @@ namespace bpkg
             // given that the deviated dependents are not very common, we just
             // postpone their re-collection.
             //
+            l5 ([&]{trace << "schedule re-collection of deviated "
+                          << "existing dependent " << *ed.selected
+                          << ed.db;});
+
             recollect_existing_dependent (options,
                                           ed,
-                                          true /* reconfigure */,
                                           replaced_vers,
                                           postponed_recs,
                                           postponed_cfgs);
@@ -3652,6 +3655,87 @@ namespace bpkg
                 throw merge_configuration {cfg.depth};
               }
 
+              // Note that there can be some non-negotiated clusters which
+              // have been merged based on the shadow cluster into the
+              // resulting (being) negotiated cluster. If we had negotiated
+              // such non-negotiated clusters normally, we would query
+              // existing dependents for the dependencies they contain and
+              // consider them in the negotiation process by re-evaluating
+              // them (see collect_build_postponed() for details). But if we
+              // force-merge a non-negotiated cluster into the (being)
+              // negotiated cluster then the existing dependents of its
+              // dependencies won't participate in the negotiation, unless we
+              // take care of that now. We will recognize such dependencies as
+              // not yet (being) recursively collected and re-collect their
+              // existing dependents, if any.
+              //
+              vector<existing_dependent> depts;
+              string deps_trace;
+
+              for (const package_key& d: cfg.dependencies)
+              {
+                build_package* p (entered_build (d));
+
+                // Must be collected at least non-recursively.
+                //
+                assert (p != nullptr);
+
+                if (p->recursive_collection)
+                  continue;
+
+                bool add_deps_trace (verb >= 5);
+
+                for (existing_dependent& ed:
+                       query_existing_dependents (trace,
+                                                  options,
+                                                  d.db,
+                                                  d.name,
+                                                  fdb,
+                                                  rpt_depts,
+                                                  replaced_vers))
+                {
+                  if (add_deps_trace)
+                  {
+                    deps_trace += p->available_name_version_db () + ' ';
+
+                    // Make sure the dependency is only listed once in the
+                    // trace record.
+                    //
+                    add_deps_trace = false;
+                  }
+
+                  // Add the existing dependent to the list, suppressing
+                  // duplicates.
+                  //
+                  if (find_if (depts.begin (), depts.end (),
+                               [&ed] (const existing_dependent& d)
+                               {
+                                 return d.selected->name == ed.selected->name &&
+                                        d.db == ed.db;
+                               }) == depts.end ())
+                  {
+                    depts.push_back (move (ed));
+                  }
+                }
+              }
+
+              if (!depts.empty ())
+              {
+                l5 ([&]{trace << "cfg-postponing dependent "
+                              << pkg.available_name_version_db ()
+                              << " adds not (being) collected dependencies "
+                              << deps_trace << "with not (being) collected "
+                              << "existing dependents to (being) negotiated "
+                              << "cluster and results in " << cfg
+                              << ", throwing recollect_existing_dependents";});
+
+                // Don't print the "while satisfying..." chain.
+                //
+                dep_chain.clear ();
+
+                throw recollect_existing_dependents {cfg.depth, move (depts)};
+              }
+
               // Up-negotiate the configuration and if it has changed, throw
               // retry_configuration to the try/catch frame corresponding to
               // the negotiation of the outermost merged cluster in order to
@@ -4809,12 +4893,6 @@ namespace bpkg
       postponed_configurations        postponed_cfgs_;
     };
 
-    struct recollect_dependent
-    {
-      size_t depth;
-      existing_dependent dependent;
-    };
-
     size_t depth (pcfg != nullptr ? pcfg->depth : 0);
 
     string t ("collect_build_postponed (" + to_string (depth) + ')');
@@ -4976,9 +5054,12 @@ namespace bpkg
               }
               else
               {
+                l5 ([&]{trace << "schedule re-collection of deviated "
+                              << "existing dependent " << *ed.selected
+                              << ed.db;});
+
                 recollect_existing_dependent (o,
                                               ed,
-                                              true /* reconfigure */,
                                               replaced_vers,
                                               postponed_recs,
                                               postponed_cfgs);
@@ -5049,9 +5130,10 @@ namespace bpkg
                 l5 ([&]{trace << "re-evaluation of existing dependent "
                               << b->available_name_version_db () << " failed "
                               << "due to merge configuration cycle for "
-                              << *pcfg << ", throwing recollect_dependent";});
+                              << *pcfg << ", throwing "
+                              << "recollect_existing_dependents";});
 
-                throw recollect_dependent {e.depth, move (ed)};
+                throw recollect_existing_dependents {e.depth, {move (ed)}};
               }
 
               ed.reevaluated = true;
@@ -5470,6 +5552,35 @@ namespace bpkg
       {
         if (!p->recursive_collection)
         {
+          package_key pk (p->db, p->name ());
+
+          auto pi (postponed_deps.find (pk));
+          if (pi != postponed_deps.end ())
+          {
+            l5 ([&]{trace << "skip re-collection of dep-postponed package "
+                          << pk;});
+
+            // Note that here we would re-collect the package without
+            // specifying any configuration for it.
+            //
+            pi->second.wout_config = true;
+
+            continue;
+          }
+          else
+          {
+            const postponed_configuration* pcfg (
+              postponed_cfgs.find_dependency (pk));
+
+            if (pcfg != nullptr)
+            {
+              l5 ([&]{trace << "skip re-collection of dep-postponed package "
+                            << pk << " since already in cluster " << *pcfg;});
+
+              continue;
+            }
+          }
+
           build_package_refs dep_chain;
           collect_build_prerequisites (o,
                                        *p,
@@ -5750,7 +5861,7 @@ namespace bpkg
 
             pc->set_shadow_cluster (move (shadow));
           }
-          catch (const recollect_dependent& e)
+          catch (const recollect_existing_dependents& e)
           {
             // If this is not "our problem", then keep looking.
             //
@@ -5784,18 +5895,23 @@ namespace bpkg
             //
             pc->shadow_cluster.clear ();
 
-            l5 ([&]{trace << "cfg-negotiation of " << *pc << " failed due "
-                          << "to merge configuration cycle while "
-                          << "re-evaluating existing dependent "
-                          << *e.dependent.selected << e.dependent.db
-                          << ", scheduling its re-collection";});
-
-            recollect_existing_dependent (o,
-                                          e.dependent,
-                                          false /* reconfigure */,
-                                          replaced_vers,
-                                          postponed_recs,
-                                          postponed_cfgs);
+            l5 ([&]{trace << "cfg-negotiation of " << *pc << " failed due to "
+                          << "some existing dependents related problem, "
+                          << "scheduling their re-collection";});
+
+            for (const existing_dependent& ed: e.dependents)
+            {
+              l5 ([&]{trace << "schedule re-collection of "
+                            << (!ed.dependency ? "deviated " : "")
+                            << "existing dependent " << *ed.selected
+                            << ed.db;});
+
+              recollect_existing_dependent (o,
+                                            ed,
+                                            replaced_vers,
+                                            postponed_recs,
+                                            postponed_cfgs);
+            }
           }
         }
       }
@@ -6732,8 +6848,9 @@ namespace bpkg
         catch (const reeval_deviated&)
         {
           r.push_back (
-            existing_dependent {
-              ddb, move (dsp), nullopt, {}, package_key {db, name}, nullopt});
+            existing_dependent {ddb, move (dsp),
+                                nullopt, {},
+                                package_key {db, name}, nullopt});
         }
       }
     }
@@ -6856,7 +6973,6 @@ namespace bpkg
   void build_packages::
   recollect_existing_dependent (const pkg_build_options& o,
                                 const existing_dependent& ed,
-                                bool reconfigure,
                                 replaced_versions& replaced_vers,
                                 postponed_packages& postponed_recs,
                                 postponed_configurations& postponed_cfgs)
@@ -6867,7 +6983,9 @@ namespace bpkg
 
     uint16_t flags (build_package::build_recollect);
 
-    if (reconfigure)
+    // Reconfigure the deviated dependents.
+    //
+    if (!ed.dependency)
       flags |= build_package::adjust_reconfigure;
 
     build_package p {
diff --git a/bpkg/pkg-build-collect.hxx b/bpkg/pkg-build-collect.hxx
index 5b4db84..1c3bc09 100644
--- a/bpkg/pkg-build-collect.hxx
+++ b/bpkg/pkg-build-collect.hxx
@@ -10,7 +10,6 @@
 #include <forward_list>
 
 #include <bpkg/types.hxx>
-#include <bpkg/forward.hxx> // database, linked_databases
 #include <bpkg/utility.hxx>
 
 #include <bpkg/package.hxx>
@@ -19,6 +18,7 @@
 #include <bpkg/common-options.hxx>
 #include <bpkg/pkg-build-options.hxx>
 
+#include <bpkg/database.hxx>
 #include <bpkg/pkg-configure.hxx>          // find_database_function()
 #include <bpkg/package-skeleton.hxx>
 #include <bpkg/system-package-manager.hxx>
@@ -441,7 +441,28 @@ namespace bpkg
   //   This, in particular, may end up in resolving different dependency
   //   packages and affect the dependent and dependency configurations.
   //
-  using postponed_packages = std::set<build_package*>;
+  // - Postponed recollection of configured dependents for resolving merge
+  //   configuration cycles and as a fallback for missed re-evaluations due to
+  //   the shadow-based configuration clusters merge (see
+  //   collect_build_prerequisites() for details).
+  //
+  // For the sake of testing, make sure the order in the set is stable.
+  //
+  struct compare_build_package
+  {
+    bool
+    operator() (const build_package* x, const build_package* y) const
+    {
+      const package_name& nx (x->name ());
+      const package_name& ny (y->name ());
+
+      if (int d = nx.compare (ny))
+        return d < 0;
+
+      return x->db.get () < y->db.get ();
+    }
+  };
+  using postponed_packages = std::set<build_package*, compare_build_package>;
 
   // Base for exception types that indicate an inability to collect a package
   // build because it was collected prematurely (version needs to be replaced,
@@ -1173,20 +1194,20 @@ namespace bpkg
     //   is {0,0}).
     //
     // - For an existing dependent being re-collected due to the selected
-    //   dependency alternatives deviation, which may be caused by its
-    //   dependency up/downgrade (see postponed prerequisites collection for
-    //   details).
+    //   dependency alternatives deviation, etc which may be caused by its
+    //   dependency up/downgrade (see postponed_packages and
+    //   build_package::build_recollect flag for details).
     //
     // Note that for these cases, as it was said above, we can potentially
     // fail if the dependent is an orphan, but this is exactly what we need to
     // do in that case, since we won't be able to re-collect its dependencies.
     //
     // Only a single true dependency alternative can be selected per function
-    // call. Such an alternative can only be selected if its index in the
-    // postponed alternatives list is less than the specified maximum (used by
-    // the heuristics that determines in which order to process packages with
-    // alternatives; if 0 is passed, then no true alternative will be
-    // selected).
+    // call, unless we are (pre-)re-evaluating. Such an alternative can only
+    // be selected if its index in the postponed alternatives list is less
+    // than the specified maximum (used by the heuristics that determines in
+    // which order to process packages with alternatives; if 0 is passed, then
+    // no true alternative will be selected).
     //
     // The idea here is to postpone the true alternatives selection till the
     // end of the packages collection and then try to optimize the overall
@@ -1203,8 +1224,11 @@ namespace bpkg
     // exception. This exception is handled via re-collecting packages from
     // scratch, but now with the knowledge about premature dependency
     // collection. If some dependency already belongs to some non or being
-    // negotiated cluster then throw merge_configuration. If some dependency
-    // configuration has already been negotiated between some other
+    // negotiated cluster then throw merge_configuration. If some dependencies
+    // have existing dependents with config clauses which have not been
+    // considered for the configuration negotiation yet, then throw
+    // recollect_existing_dependents exception to re-collect these dependents.
+    // If configuration has already been negotiated between some other
     // dependents, then up-negotiate the configuration and throw
     // retry_configuration exception so that the configuration refinement can
     // be performed. See the collect lambda implementation for details on the
@@ -1476,6 +1500,17 @@ namespace bpkg
       optional<pair<size_t, size_t>> orig_dependency_position;
     };
 
+    // This exception is thrown by collect_build_prerequisites() and
+    // collect_build_postponed() to resolve different kinds of existing
+    // dependent re-evaluation related cycles by re-collecting the problematic
+    // dependents from scratch.
+    //
+    struct recollect_existing_dependents
+    {
+      size_t depth;
+      vector<existing_dependent> dependents;
+    };
+
     vector<existing_dependent>
     query_existing_dependents (
       tracer&,
@@ -1509,14 +1544,19 @@ namespace bpkg
       replaced_versions&,
       postponed_configurations&);
 
-    // Non-recursively collect the deviated existing dependent previously
-    // returned by the query_existing_dependents() function call and add it to
-    // the postponed package recollections list.
+    // Non-recursively collect an existing dependent previously returned by
+    // the query_existing_dependents() function call with the
+    // build_package::build_recollect flag and add it to the postponed package
+    // recollections list. Also add the build_package::adjust_reconfigure flag
+    // for the deviated dependents (existing_dependent::dependency is absent).
+    //
+    // Note that after this function call the existing dependent may not be
+    // returned as a result by the query_existing_dependents() function
+    // anymore (due to the build_package::build_recollect flag presence).
     //
     void
     recollect_existing_dependent (const pkg_build_options&,
                                   const existing_dependent&,
-                                  bool reconfigure,
                                   replaced_versions&,
                                   postponed_packages& postponed_recs,
                                   postponed_configurations&);
diff --git a/tests/pkg-build.testscript b/tests/pkg-build.testscript
index 442349f..d8e6a94 100644
--- a/tests/pkg-build.testscript
+++ b/tests/pkg-build.testscript
@@ -223,9 +223,10 @@
 # |   |-- bas-1.0.0.tar.gz      -> libbar {require {config.libbar.extras=true}},
 # |   |                            bus {require {config.bus.extras=true}}
 # |   |-- bus-0.1.0.tar.gz      -> foo {require {config.foo.extras=true}}
-# |   |-- bus-1.0.0.tar.gz      -> libaz {require {config.libbox.extras=true}},
+# |   |-- bus-1.0.0.tar.gz      -> libaz {require {config.libbaz.extras=true}},
 # |   |                            foo {require {config.foo.extras=true}}
-# |   |-- box-0.1.0.tar.gz      -> libbox {require {config.libbox.extras=true}}
+# |   |-- box-0.1.0.tar.gz      -> libbox == 0.1.0 {require {config.libbox.extras=true}}
+# |   |-- box-0.2.0.tar.gz      -> libbox {require {config.libbox.extras=true}}
 # |   |-- box-1.0.0.tar.gz      -> {libbar libfoo} {require {config.libbar.extras=true config.libfoo.extras=true}} |
 # |   |                            libbox
 # |   |-- bax-0.1.0.tar.gz      -> {libbox libbar} {require {config.libbox.extras=true}}
@@ -7304,6 +7305,8 @@ test.arguments += --sys-no-query
               trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
               trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{baz/1,1}}?
               %.*
+              trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbox
+              %.*
               trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{bax/2,1 baz/1,1} libbox->{bax/2,1}}?, throwing retry_configuration
               trace: collect_build_postponed (0): cfg-negotiation of {bax^ | libfoo->{bax/1,1}} failed due to dependent bax, refining configuration
               trace: collect_build_postponed (1): begin {bax^ | libfoo->{bax/1,1}}
@@ -7342,6 +7345,8 @@ test.arguments += --sys-no-query
               trace: collect_build_prerequisites: cfg-postpone dependency libbox/0.1.0 of dependent bax/1.0.0
               trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
               trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{baz/1,1}}?
+              %.*
+              trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbox
               trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
               trace: collect_build_prerequisites: collecting cfg-postponed dependency libbox/0.1.0 of dependent bax/1.0.0
               trace: collect_build_prerequisites: begin libbox/0.1.0
@@ -7623,6 +7628,8 @@ test.arguments += --sys-no-query
               trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
               trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{baz/1,1}}?
               %.*
+              trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbox
+              %.*
               trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{bax/2,1 baz/1,1} libbox->{bax/2,1}}?, throwing retry_configuration
               trace: collect_build_postponed (0): cfg-negotiation of {bax^ | libfoo->{bax/1,1}} failed due to dependent bax, refining configuration
               trace: collect_build_postponed (1): begin {bax^ | libfoo->{bax/1,1}}
@@ -7660,6 +7667,8 @@ test.arguments += --sys-no-query
               trace: collect_build_prerequisites: cfg-postpone dependency libbox/0.1.0 of dependent bax/1.0.0
               trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
               trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bax^ baz^ | libfoo->{bax/1,1 baz/1,1} libbar->{baz/1,1}}?
+              %.*
+              trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbox
               trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
               trace: collect_build_prerequisites: collecting cfg-postponed dependency libbox/0.1.0 of dependent bax/1.0.0
               trace: collect_build_prerequisites: begin libbox/0.1.0
@@ -8364,6 +8373,7 @@ test.arguments += --sys-no-query
           trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
           trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
           trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {bar bas bix | libbar->{bar/1,1 bas/1,1 bix/1,1} bar->{bix/1,1}}!
+          %.*
           trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
           trace: collect_build_prerequisites: collecting cfg-postponed dependency libbox/1.0.0 of dependent bax/1.0.0
           trace: collect_build_prerequisites: begin libbox/1.0.0
@@ -15685,8 +15695,9 @@ test.arguments += --sys-no-query
         %.*
         trace: postponed_configurations::add: add {tex^ 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
         trace: collect_build_prerequisites: merge configuration cycle detected for being re-evaluated dependent tex/1.0.0 since {box tex^ | libbox->{box/1,1} libbar->{tex/1,1}}! is a shadow of itself, throwing merge_configuration_cycle
-        trace: collect_build_postponed (2): re-evaluation of existing dependent tex/1.0.0 failed due to merge configuration cycle for {bax^ | libfoo->{bax/1,1}}, throwing recollect_dependent
-        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to merge configuration cycle while re-evaluating existing dependent tex/1.0.0, scheduling its re-collection
+        trace: collect_build_postponed (2): re-evaluation of existing dependent tex/1.0.0 failed due to merge configuration cycle for {bax^ | libfoo->{bax/1,1}}, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tex/1.0.0
         trace: collect_build: add tex/1.0.0
         trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
         %.*
@@ -15759,6 +15770,9 @@ test.arguments += --sys-no-query
         trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
         trace: postponed_configurations::add: add {tex 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
         %.*
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        %.*
         trace: collect_build_prerequisites: cfg-postponing dependent tex/1.0.0 involves (being) negotiated configurations and results in {box tex | libbox->{box/1,1} libbar->{tex/1,1}}!, throwing retry_configuration
         trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to dependent tex, refining configuration
         trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
@@ -15787,6 +15801,9 @@ test.arguments += --sys-no-query
         trace: collect_build: add libbar/1.0.0
         trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
         trace: postponed_configurations::add: add {tex 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
         trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tex/1.0.0 is shadow-negotiated
         trace: collect_build_prerequisites: collecting cfg-postponed dependency libbar/1.0.0 of dependent tex/1.0.0
         trace: collect_build_prerequisites: skip configured libbar/1.0.0
@@ -15842,6 +15859,1079 @@ test.arguments += --sys-no-query
       $pkg_drop bax tex box
     }
 
+    : up-negotiate-not-collected-existing-dependents
+    :
+    {
+      $clone_cfg;
+
+      #  Dependencies:
+      #
+      #  bax: depends: libfoo(c)
+      #       depends: {libbox libbar} (c)
+      #
+      #  tiz: depends: tex(c)
+      #       depends: libbar(c)
+      #
+      #  tex: depends: libbar(c)
+      #       depends: libfoo(c)
+      #
+      #  box/0.1.0: depends: libbox(c)
+      #
+      $* bax tiz 2>!;
+
+      $pkg_status -r >>EOO;
+        !bax configured 1.0.0
+          libbar configured 1.0.0
+          libbox configured 1.0.0
+          libfoo configured 1.0.0
+        !tiz configured 1.0.0
+          libbar configured 1.0.0
+          tex configured 1.0.0
+            libbar configured 1.0.0
+            libfoo configured 1.0.0
+        EOO
+
+      $* box/0.2.0 2>>~%EOE%;
+        %.*
+        trace: pkg_build: refine package collection/plan execution from scratch
+        %.*
+        trace: collect_build: add box/0.2.0
+        trace: collect_build_prerequisites: begin box/0.2.0
+        %.*
+        trace: collect_build: add libbox/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent box/0.2.0
+        trace: postponed_configurations::add: create {box | libbox->{box/1,1}}
+        trace: collect_build_prerequisites: postpone box/0.2.0
+        trace: collect_build_postponed (0): begin
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {tex^ | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent tex/1.0.0 results in {tex^ | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: re-evaluated tex/1.0.0
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {box | libbox->{box/1,1}}!
+        trace: postponed_configurations::add: merge {tex^ | libbar->{tex/1,1}} into {bax box | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 merges non-negotiated and/or being negotiated configurations in and results in {bax box tex^ | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1 tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {bax box tex^ | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1 tex/1,1}}!
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: add {tex^ 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
+        trace: collect_build_prerequisites: re-evaluating dependent tex/1.0.0 involves negotiated configurations and results in {box tex^ | libbox->{box/1,1} libbar->{tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {box tex^ | libbox->{box/1,1} libbar->{tex/1,1}}!
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: add {tex^ 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
+        trace: collect_build_prerequisites: merge configuration cycle detected for being re-evaluated dependent tex/1.0.0 since {box tex^ | libbox->{box/1,1} libbar->{tex/1,1}}! is a shadow of itself, throwing merge_configuration_cycle
+        trace: collect_build_postponed (2): re-evaluation of existing dependent tex/1.0.0 failed due to merge configuration cycle for {bax^ | libfoo->{bax/1,1}}, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tex/1.0.0
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: create {tex | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: postpone tex/1.0.0
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {box | libbox->{box/1,1}}!
+        trace: postponed_configurations::add: merge {tex | libbar->{tex/1,1}} into {bax box | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 merges non-negotiated and/or being negotiated configurations in and results in {bax box tex | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1 tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {bax box tex | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1 tex/1,1}}!
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 1,1: libbar} to {box | libbox->{box/1,1}}! (shadow cluster-based)
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tiz/1.0.0: 1,1
+        trace: collect_build_prerequisites: cfg-postponing dependent tex/1.0.0 adds not (being) collected dependencies libbar/1.0.0 with not (being) collected existing dependents to (being) negotiated cluster and results in {box tex | libbox->{box/1,1} libbar->{tex/1,1}}!, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tiz/1.0.0
+        trace: collect_build: add tiz/1.0.0
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: create {tex | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: postpone tex/1.0.0
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cannot cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0 (collected prematurely), throwing postpone_dependency
+        trace: pkg_build: collection failed due to prematurely collected dependency (tex), retry from scratch
+        %.*
+        trace: pkg_build: refine package collection/plan execution from scratch
+        %.*
+        trace: collect_build: add box/0.2.0
+        trace: collect_build_prerequisites: begin box/0.2.0
+        %.*
+        trace: collect_build: add libbox/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent box/0.2.0
+        trace: postponed_configurations::add: create {box | libbox->{box/1,1}}
+        trace: collect_build_prerequisites: postpone box/0.2.0
+        trace: collect_build_postponed (0): begin
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): skip dep-postponed existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {box | libbox->{box/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: pre-reeval tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tiz/1.0.0: 1,1
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 adds not (being) collected dependencies libbar/1.0.0 with not (being) collected existing dependents to (being) negotiated cluster and results in {bax box | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1}}!, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tex/1.0.0
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tiz/1.0.0
+        trace: collect_build: add tiz/1.0.0
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: create {tiz | tex->{tiz/1,1}}
+        trace: collect_build_prerequisites: postpone tiz/1.0.0
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {box | libbox->{box/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tiz of dependency libbar
+        %.*
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bax box | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1}}!, throwing retry_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {box | libbox->{box/1,1}} failed due to dependent bax, refining configuration
+        trace: collect_build_postponed (1): begin {box | libbox->{box/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {box | libbox->{box/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent box/0.2.0
+        trace: collect_build_prerequisites: resume box/0.2.0
+        trace: collect_build_prerequisites: end box/0.2.0
+        trace: collect_build_postponed (1): cfg-negotiate end {box | libbox->{box/1,1}}!
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: create {tiz | tex->{tiz/1,1}}
+        trace: collect_build_prerequisites: postpone tiz/1.0.0
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {box | libbox->{box/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tiz of dependency libbar
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbox/1.0.0 of dependent bax/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: collecting cfg-postponed dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: skip configured libbar/1.0.0
+        trace: collect_build_prerequisites: end bax/1.0.0
+        trace: collect_build_postponed (2): cfg-negotiate end {bax^ | libfoo->{bax/1,1}}!
+        trace: collect_build_postponed (2): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (3): begin {tiz | tex->{tiz/1,1}}
+        %.*
+        trace: collect_build_postponed (3): skip being built existing dependent tiz of dependency tex
+        trace: collect_build_postponed (3): cfg-negotiate begin {tiz | tex->{tiz/1,1}}
+        %.*
+        trace: collect_build_postponed (3): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 1,1: libbar} to {bax box | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tex/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent tex/1.0.0 is already (being) recursively collected, skipping
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 2,1: libfoo} to {bax^ | libfoo->{bax/1,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tex/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libfoo/1.0.0 of dependent tex/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: end tex/1.0.0
+        trace: collect_build_postponed (3): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (3): select cfg-negotiated dependency alternative for dependent tiz/1.0.0
+        trace: collect_build_prerequisites: resume tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: add {tiz 2,1: libbar} to {bax box tex | libbox->{bax/2,1 box/1,1} libbar->{bax/2,1 tex/1,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tiz/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent tiz/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: end tiz/1.0.0
+        trace: collect_build_postponed (3): cfg-negotiate end {tiz | tex->{tiz/1,1}}!
+        trace: collect_build_postponed (3): end {tiz | tex->{tiz/1,1}}
+        trace: collect_build_postponed (2): end {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (1): end {box | libbox->{box/1,1}}
+        trace: collect_build_postponed (0): end
+        trace: execute_plan: simulate: yes
+        %.*
+        build plan:
+          new box/0.2.0
+        trace: execute_plan: simulate: no
+        %.*
+        EOE
+
+      $pkg_status -r >>EOO;
+        !bax configured 1.0.0
+          libbar configured 1.0.0
+          libbox configured 1.0.0
+          libfoo configured 1.0.0
+        !tiz configured 1.0.0
+          libbar configured 1.0.0
+          tex configured 1.0.0
+            libbar configured 1.0.0
+            libfoo configured 1.0.0
+        !box configured !0.2.0 available 1.0.0
+          libbox configured 1.0.0
+        EOO
+
+      $pkg_drop bax tiz box
+    }
+
+    : up-negotiate-not-collected-existing-dependents2
+    :
+    : Similar to the above but more complicated.
+    :
+    {
+      $clone_cfg;
+
+      #  Dependencies:
+      #
+      #  bax: depends: libfoo(c)
+      #       depends: {libbox libbar} (c)
+      #
+      #  tiz: depends: tex(c)
+      #       depends: libbar(c)
+      #
+      #  tex: depends: libbar(c)
+      #       depends: libfoo(c)
+      #
+      #  tez: depends: libbox(c)
+      #       depends: toz == 0.1.0 (c)
+      #       depends: libbar(c)
+      #
+      #  toz/0.1.0:
+      #
+      $* bax tiz 2>!;
+
+      $pkg_status -r >>EOO;
+        !bax configured 1.0.0
+          libbar configured 1.0.0
+          libbox configured 1.0.0
+          libfoo configured 1.0.0
+        !tiz configured 1.0.0
+          libbar configured 1.0.0
+          tex configured 1.0.0
+            libbar configured 1.0.0
+            libfoo configured 1.0.0
+        EOO
+
+      $* tez 2>>~%EOE%;
+        %.*
+        trace: pkg_build: refine package collection/plan execution from scratch
+        %.*
+        trace: collect_build: add tez/1.0.0
+        trace: collect_build_prerequisites: begin tez/1.0.0
+        %.*
+        trace: collect_build: add libbox/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | libbox->{tez/1,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (0): begin
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {tex^ | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent tex/1.0.0 results in {tex^ | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: re-evaluated tex/1.0.0
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {tez | libbox->{tez/1,1}}!
+        trace: postponed_configurations::add: merge {tex^ | libbar->{tex/1,1}} into {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 merges non-negotiated and/or being negotiated configurations in and results in {bax tex^ tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {bax tex^ tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tex/1,1}}!
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: add {tex^ 1,1: libbar} to {tez | libbox->{tez/1,1}}! (shadow cluster-based)
+        trace: collect_build_prerequisites: re-evaluating dependent tex/1.0.0 involves negotiated configurations and results in {tex^ tez | libbox->{tez/1,1} libbar->{tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {tex^ tez | libbox->{tez/1,1} libbar->{tex/1,1}}!
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_postponed (2): re-evaluate existing dependents for {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_prerequisites: reeval tex/1.0.0
+        %.*
+        trace: postponed_configurations::add: add {tex^ 1,1: libbar} to {tez | libbox->{tez/1,1}}! (shadow cluster-based)
+        trace: collect_build_prerequisites: merge configuration cycle detected for being re-evaluated dependent tex/1.0.0 since {tex^ tez | libbox->{tez/1,1} libbar->{tex/1,1}}! is a shadow of itself, throwing merge_configuration_cycle
+        trace: collect_build_postponed (2): re-evaluation of existing dependent tex/1.0.0 failed due to merge configuration cycle for {bax^ | libfoo->{bax/1,1}}, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tex/1.0.0
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: create {tex | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: postpone tex/1.0.0
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {tez | libbox->{tez/1,1}}!
+        trace: postponed_configurations::add: merge {tex | libbar->{tex/1,1}} into {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 merges non-negotiated and/or being negotiated configurations in and results in {bax tex tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tex/1,1}}!, throwing merge_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to non-negotiated clusters, force-merging based on shadow cluster {bax tex tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tex/1,1}}!
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 1,1: libbar} to {tez | libbox->{tez/1,1}}! (shadow cluster-based)
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tiz/1.0.0: 1,1
+        trace: collect_build_prerequisites: cfg-postponing dependent tex/1.0.0 adds not (being) collected dependencies libbar/1.0.0 with not (being) collected existing dependents to (being) negotiated cluster and results in {tex tez | libbox->{tez/1,1} libbar->{tex/1,1}}!, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tiz/1.0.0
+        trace: collect_build: add tiz/1.0.0
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: create {tex | libbar->{tex/1,1}}
+        trace: collect_build_prerequisites: postpone tex/1.0.0
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cannot cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0 (collected prematurely), throwing postpone_dependency
+        trace: pkg_build: collection failed due to prematurely collected dependency (tex), retry from scratch
+        %.*
+        trace: pkg_build: refine package collection/plan execution from scratch
+        %.*
+        trace: collect_build: add tez/1.0.0
+        trace: collect_build_prerequisites: begin tez/1.0.0
+        %.*
+        trace: collect_build: add libbox/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | libbox->{tez/1,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (0): begin
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): skip dep-postponed existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {tez | libbox->{tez/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: pre-reeval tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tex/1.0.0: 1,1
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: pre-reeval tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated tiz/1.0.0: 1,1
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 adds not (being) collected dependencies libbar/1.0.0 with not (being) collected existing dependents to (being) negotiated cluster and results in {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1}}!, throwing recollect_existing_dependents
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to some existing dependents related problem, scheduling their re-collection
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tex/1.0.0
+        trace: collect_build: add tex/1.0.0
+        trace: collect_build_postponed (0): schedule re-collection of existing dependent tiz/1.0.0
+        trace: collect_build: add tiz/1.0.0
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: create {tiz | tex->{tiz/1,1}}
+        trace: collect_build_prerequisites: postpone tiz/1.0.0
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {tez | libbox->{tez/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tiz of dependency libbar
+        %.*
+        trace: collect_build_prerequisites: cfg-postponing dependent bax/1.0.0 involves (being) negotiated configurations and results in {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1}}!, throwing retry_configuration
+        trace: collect_build_postponed (0): cfg-negotiation of {tez | libbox->{tez/1,1}} failed due to dependent bax, refining configuration
+        trace: collect_build_postponed (1): begin {tez | libbox->{tez/1,1}}
+        %.*
+        trace: collect_build_prerequisites: pre-reeval bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: pre-reevaluated bax/1.0.0: 1,1
+        trace: collect_build: add libfoo/1.0.0
+        trace: collect_build_postponed (1): re-evaluate existing dependents for {tez | libbox->{tez/1,1}}
+        trace: collect_build: add bax/1.0.0
+        trace: collect_build_prerequisites: reeval bax/1.0.0
+        %.*
+        trace: postponed_configurations::add: create {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluating dependent bax/1.0.0 results in {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_prerequisites: re-evaluated bax/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate begin {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libbox/1.0.0
+        trace: collect_build_postponed (1): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (1): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build: add toz/0.1.0
+        trace: collect_build_prerequisites: cfg-postpone dependency toz/0.1.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: create {tez | toz->{tez/2,1}}
+        trace: collect_build_prerequisites: postpone tez/1.0.0
+        trace: collect_build_postponed (1): cfg-negotiate end {tez | libbox->{tez/1,1}}!
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_prerequisites: begin tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency tex/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: create {tiz | tex->{tiz/1,1}}
+        trace: collect_build_prerequisites: postpone tiz/1.0.0
+        trace: collect_build_postponed (1): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (2): begin {bax^ | libfoo->{bax/1,1}}
+        %.*
+        trace: collect_build_postponed (2): skip being built existing dependent tex of dependency libfoo
+        trace: collect_build_postponed (2): skip being built existing dependent bax of dependency libfoo
+        trace: collect_build_postponed (2): cfg-negotiate begin {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: skip configured libfoo/1.0.0
+        trace: collect_build_postponed (2): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (2): select cfg-negotiated dependency alternative for dependent bax/1.0.0
+        trace: collect_build_prerequisites: resume bax/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbox/1.0.0 of dependent bax/1.0.0
+        trace: collect_build: add libbar/1.0.0
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: postponed_configurations::add: add {bax 2,1: libbox libbar} to {tez | libbox->{tez/1,1}}!
+        %.*
+        trace: collect_build_prerequisites: skip being built existing dependent tex of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent bax of dependency libbar
+        trace: collect_build_prerequisites: skip being built existing dependent tiz of dependency libbar
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent bax/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbox/1.0.0 of dependent bax/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: collecting cfg-postponed dependency libbar/1.0.0 of dependent bax/1.0.0
+        trace: collect_build_prerequisites: skip configured libbar/1.0.0
+        trace: collect_build_prerequisites: end bax/1.0.0
+        trace: collect_build_postponed (2): cfg-negotiate end {bax^ | libfoo->{bax/1,1}}!
+        trace: collect_build_postponed (2): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (3): begin {tez | toz->{tez/2,1}}
+        %.*
+        trace: collect_build_postponed (3): cfg-negotiate begin {tez | toz->{tez/2,1}}
+        %.*
+        trace: collect_build_postponed (3): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: begin toz/0.1.0
+        trace: collect_build_prerequisites: end toz/0.1.0
+        trace: collect_build_postponed (3): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (3): select cfg-negotiated dependency alternative for dependent tez/1.0.0
+        trace: collect_build_prerequisites: resume tez/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tez/1.0.0
+        trace: postponed_configurations::add: add {tez 3,1: libbar} to {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tez/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent tez/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: end tez/1.0.0
+        trace: collect_build_postponed (3): cfg-negotiate end {tez | toz->{tez/2,1}}!
+        trace: collect_build_postponed (3): skip re-collection of dep-postponed package tex
+        trace: collect_build_postponed (4): begin {tiz | tex->{tiz/1,1}}
+        %.*
+        trace: collect_build_postponed (4): skip being built existing dependent tiz of dependency tex
+        trace: collect_build_postponed (4): cfg-negotiate begin {tiz | tex->{tiz/1,1}}
+        %.*
+        trace: collect_build_postponed (4): recursively collect cfg-negotiated dependencies
+        trace: collect_build_prerequisites: begin tex/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 1,1: libbar} to {bax tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tez/3,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tex/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent tex/1.0.0 is already (being) recursively collected, skipping
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libfoo/1.0.0 of dependent tex/1.0.0
+        trace: postponed_configurations::add: add {tex 2,1: libfoo} to {bax^ | libfoo->{bax/1,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tex/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libfoo/1.0.0 of dependent tex/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: end tex/1.0.0
+        trace: collect_build_postponed (4): recursively collect cfg-negotiated dependents
+        trace: collect_build_postponed (4): select cfg-negotiated dependency alternative for dependent tiz/1.0.0
+        trace: collect_build_prerequisites: resume tiz/1.0.0
+        %.*
+        trace: collect_build_prerequisites: cfg-postpone dependency libbar/1.0.0 of dependent tiz/1.0.0
+        trace: postponed_configurations::add: add {tiz 2,1: libbar} to {bax tex tez | libbox->{bax/2,1 tez/1,1} libbar->{bax/2,1 tex/1,1 tez/3,1}}!
+        trace: collect_build_prerequisites: configuration for cfg-postponed dependencies of dependent tiz/1.0.0 is negotiated
+        trace: collect_build_prerequisites: dependency libbar/1.0.0 of dependent tiz/1.0.0 is already (being) recursively collected, skipping
+        trace: collect_build_prerequisites: end tiz/1.0.0
+        trace: collect_build_postponed (4): cfg-negotiate end {tiz | tex->{tiz/1,1}}!
+        trace: collect_build_postponed (4): end {tiz | tex->{tiz/1,1}}
+        trace: collect_build_postponed (3): end {tez | toz->{tez/2,1}}
+        trace: collect_build_postponed (2): end {bax^ | libfoo->{bax/1,1}}
+        trace: collect_build_postponed (1): end {tez | libbox->{tez/1,1}}
+        trace: collect_build_postponed (0): end
+        trace: execute_plan: simulate: yes
+        %.*
+        build plan:
+          new toz/0.1.0 (required by tez)
+            config.toz.extras=true (set by tez)
+          new tez/1.0.0
+        trace: execute_plan: simulate: no
+        %.*
+        EOE
+
+      $pkg_status -r >>EOO;
+        !bax configured 1.0.0
+          libbar configured 1.0.0
+          libbox configured 1.0.0
+          libfoo configured 1.0.0
+        !tiz configured 1.0.0
+          libbar configured 1.0.0
+          tex configured 1.0.0
+            libbar configured 1.0.0
+            libfoo configured 1.0.0
+        !tez configured 1.0.0
+          libbar configured 1.0.0
+          libbox configured 1.0.0
+          toz configured 0.1.0 available 1.0.0 0.2.0
+        EOO
+
+      $pkg_drop bax tiz tez
+    }
+
     : all-repo-packages
     :
     : Don't match the tracing but just make sure that pkg-build doesn't crash