--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -872,7 +872,7 @@ class localrepository(object):
b = []
for n in nodes:
t = n
- while n:
+ while 1:
p = self.changelog.parents(n)
if p[1] != nullid or p[0] == nullid:
b.append((t, n, p[0], p[1]))