--- a/mercurial/localrepo.py	Wed Jan 21 11:15:47 2009 -0600
+++ b/mercurial/localrepo.py	Sun Jan 25 10:16:45 2009 -0600
@@ -1237,7 +1237,7 @@
             n, l, i = top, [], 0
             f = 1
 
-            while n != bottom:
+            while n != bottom and n != nullid:
                 p = self.changelog.parents(n)[0]
                 if i == f:
                     l.append(n)