--- a/mercurial/localrepo.py	Tue Dec 18 12:47:20 2012 -0800
+++ b/mercurial/localrepo.py	Mon Dec 17 20:43:37 2012 -0800
@@ -2081,7 +2081,7 @@
             bases = [nullid]
         csets, bases, heads = cl.nodesbetween(bases, heads)
         # We assume that all ancestors of bases are known
-        common = set(cl.ancestors([cl.rev(n) for n in bases]))
+        common = cl.ancestors([cl.rev(n) for n in bases])
         return self._changegroupsubset(common, csets, heads, source)
 
     def getlocalbundle(self, source, outgoing):