diff -r ea585f2b1adc -r 4d958d1bb072 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Sat Mar 26 13:05:17 2011 +0100
+++ b/mercurial/localrepo.py	Mon Mar 14 23:50:28 2011 +0100
@@ -1024,10 +1024,7 @@
                 raise
 
             # update bookmarks, dirstate and mergestate
-            parents = (p1, p2)
-            if p2 == nullid:
-                parents = (p1,)
-            bookmarks.update(self, parents, ret)
+            bookmarks.update(self, p1, ret)
             for f in changes[0] + changes[1]:
                 self.dirstate.normal(f)
             for f in changes[2]: