Rev 2409: Better assertion message from InterDirStateTree._iter_changes in http://sourcefrog.net/bzr/dirstate

[Martin Pool]

At http://sourcefrog.net/bzr/dirstate

------------------------------------------------------------
revno: 2409
revision-id: mbp at sourcefrog.net-20070226031951-yd7bashmx3mjkmep
parent: mbp at sourcefrog.net-20070226031310-7alk7pvlb8fg0asn
committer: Martin Pool <mbp at sourcefrog.net>
branch nick: dirstate
timestamp: Mon 2007-02-26 14:19:51 +1100
message:
  Better assertion message from InterDirStateTree._iter_changes
modified:
  bzrlib/workingtree_4.py        workingtree_4.py-20070208044105-5fgpc5j3ljlh5q6c-1
=== modified file 'bzrlib/workingtree_4.py'
--- a/bzrlib/workingtree_4.py	2007-02-26 03:13:10 +0000
+++ b/bzrlib/workingtree_4.py	2007-02-26 03:19:51 +0000
@@ -1405,7 +1405,10 @@
                 require_versioned):
                 yield f
             return
-        assert (self.source._revision_id in self.target.get_parent_ids())
+        assert (self.source._revision_id in self.target.get_parent_ids()), \
+                "revision {%s} is not stored in {%s}, but %s " \
+                "can only be used for trees stored in the dirstate" \
+                % (self.source._revision_id, self.target, self._iter_changes)
         parents = self.target.get_parent_ids()
         target_index = 0
         source_index = 1 + parents.index(self.source._revision_id)