--- a/hgext/rebase.py	Mon Apr 04 16:21:57 2011 -0500
+++ b/hgext/rebase.py	Mon Apr 04 16:21:59 2011 -0500
@@ -300,7 +300,7 @@
     repo.ui.debug(" merge against %d:%s\n" % (repo[rev].rev(), repo[rev]))
     base = None
     if repo[rev].rev() != repo[min(state)].rev():
-        base = repo[rev].parents()[0].node()
+        base = repo[rev].p1().node()
     return merge.update(repo, rev, True, True, False, base)
 
 def defineparents(repo, rev, target, state, targetancestors):