--- a/mercurial/phases.py	Mon Jan 30 18:06:57 2012 +0100
+++ b/mercurial/phases.py	Mon Jan 30 17:33:09 2012 +0100
@@ -122,6 +122,7 @@
             raise
         for f in repo._phasedefaults:
             roots = f(repo, roots)
+        repo._dirtyphases = True
     return roots
 
 def writeroots(repo):