--- a/mercurial/localrepo.py	Mon Nov 07 12:27:25 2011 +0100
+++ b/mercurial/localrepo.py	Mon Nov 07 13:20:22 2011 +0100
@@ -174,7 +174,9 @@
     @filecache('phaseroots')
     def _phaseroots(self):
         self._dirtyphases = False
-        return phases.readroots(self)
+        phaseroots = phases.readroots(self)
+        phases.filterunknown(self, phaseroots)
+        return phaseroots
 
     @propertycache
     def _phaserev(self):