diff -r aaaa7ebc578b -r 2aa5b51f310f mercurial/phases.py
--- a/mercurial/phases.py	Wed Feb 01 17:59:51 2012 -0200
+++ b/mercurial/phases.py	Wed Feb 01 14:17:26 2012 -0600
@@ -239,6 +239,9 @@
         if currentphase == oldphase and newphase < oldphase:
             advanceboundary(repo, newphase, [bin(nhex)])
             return 1
+        elif currentphase == newphase:
+            # raced, but got correct result
+            return 1
         else:
             return 0
     finally: