--- a/mercurial/bundlerepo.py	Sat May 12 16:00:53 2012 +0200
+++ b/mercurial/bundlerepo.py	Sat May 12 16:00:57 2012 +0200
@@ -54,7 +54,7 @@
                 continue
 
             for p in (p1, p2):
-                if not p in self.nodemap:
+                if p not in self.nodemap:
                     raise error.LookupError(p, self.indexfile,
                                             _("unknown parent"))
             # start, size, full unc. size, base (unused), link, p1, p2, node