depgraph: don't _skip_restart for blockers

This prevents blockers from interfering with backtracking, as reported
in bug #465356, comment #15.

diff --git a/pym/_emerge/depgraph.py b/pym/_emerge/depgraph.py
index a00c7fb03506d86f9643c850ab808da9514d4abc..99b96bf2f494516bfbaf0ee0874c092a56fe6992 100644 (file)
--- a/pym/_emerge/depgraph.py
+++ b/pym/_emerge/depgraph.py
@@ -5813,7 +5813,9 @@ class depgraph(object):
                self._slot_operator_trigger_reinstalls()
 
                if not self._validate_blockers():
-                       self._dynamic_config._skip_restart = True
+                       # Blockers don't trigger the _skip_restart flag, since
+                       # backtracking may solve blockers when it solves slot
+                       # conflicts (or by blind luck).
                        raise self._unknown_internal_error()
 
        def _serialize_tasks(self):
@@ -6562,7 +6564,9 @@ class depgraph(object):
                        self._dynamic_config._unsatisfied_blockers_for_display = unsolvable_blockers
                        self._dynamic_config._serialized_tasks_cache = retlist[:]
                        self._dynamic_config._scheduler_graph = scheduler_graph
-                       self._dynamic_config._skip_restart = True
+                       # Blockers don't trigger the _skip_restart flag, since
+                       # backtracking may solve blockers when it solves slot
+                       # conflicts (or by blind luck).
                        raise self._unknown_internal_error()
 
                if self._dynamic_config._slot_collision_info and \