phases: introduce phasecache The original motivation was changectx.phase() had special logic to correctly lookup in repo._phaserev, including invalidating it when necessary. And at other places, repo._phaserev was accessed directly. This led to the discovery that phases state including _phaseroots, _phaserev and _dirtyphase was manipulated in localrepository.py, phases.py, repair.py, etc. phasecache helps encapsulating that. This patch replaces all phase state in localrepo with phasecache and adjust related code except for advance/retractboundary() in phases. These still access to phasecache internals directly. This will be addressed in a followup.

--- a/hgext/mq.py	Sat May 12 00:19:30 2012 +0200
+++ b/hgext/mq.py	Sat May 12 00:24:07 2012 +0200
@@ -883,7 +883,7 @@
     def finish(self, repo, revs):
         # Manually trigger phase computation to ensure phasedefaults is
         # executed before we remove the patches.
-        repo._phaserev
+        repo._phasecache
         patches = self._revpatches(repo, sorted(revs))
         qfinished = self._cleanup(patches, len(patches))
         if qfinished and repo.ui.configbool('mq', 'secret', False):