--- a/mercurial/revset.py	Wed Apr 30 15:36:38 2014 -0700
+++ b/mercurial/revset.py	Sat Apr 26 00:38:02 2014 -0700
@@ -2797,9 +2797,9 @@
         if isinstance(x, baseset):
             x = x.set()
         if self._start <= self._end:
-            return orderedlazyset(self, lambda r: r in x)
+            return orderedlazyset(self, x.__contains__)
         else:
-            return orderedlazyset(self, lambda r: r in x, ascending=False)
+            return orderedlazyset(self, x.__contains__, ascending=False)
 
     def __sub__(self, x):
         if isinstance(x, baseset):