mercurial/revset.py

--- a/mercurial/revset.py	Thu Mar 13 11:36:45 2014 -0700
+++ b/mercurial/revset.py	Fri Mar 14 11:41:26 2014 -0700
@@ -2174,7 +2174,7 @@
 
     Every method in this class should be implemented by any smartset class.
     """
-    def __init__(self, data):
+    def __init__(self, data=()):
         super(baseset, self).__init__(data)
         self._set = None