diff -r f9a825b593be -r 5308f21c049e mercurial/revset.py
--- a/mercurial/revset.py	Fri Oct 03 12:36:08 2014 -0500
+++ b/mercurial/revset.py	Fri Oct 03 12:36:57 2014 -0500
@@ -2703,6 +2703,10 @@
     This class does not duck-type baseset and it's only supposed to be used
     internally
     """
+
+    def __init__(self, gen):
+        super(_ascgeneratorset, self).__init__(gen, iterasc=True)
+
     def __contains__(self, x):
         if x in self._cache:
             return self._cache[x]
@@ -2726,6 +2730,10 @@
     This class does not duck-type baseset and it's only supposed to be used
     internally
     """
+
+    def __init__(self, gen):
+        super(_descgeneratorset, self).__init__(gen, iterasc=False)
+
     def __contains__(self, x):
         if x in self._cache:
             return self._cache[x]