--- a/mercurial/revset.py	Sat Jan 10 13:14:00 2015 +0900
+++ b/mercurial/revset.py	Sun Jan 25 20:20:27 2015 +0900
@@ -31,7 +31,7 @@
             revsnode = revqueue.popleft()
             heapq.heappush(h, -revsnode)
 
-        seen = set([node.nullrev])
+        seen = set()
         while h:
             current = -heapq.heappop(h)
             if current not in seen: