--- a/mercurial/fancyopts.py	Mon Jun 23 09:23:57 2014 -0400
+++ b/mercurial/fancyopts.py	Mon Jun 23 09:24:16 2014 -0400
@@ -77,7 +77,7 @@
         # copy defaults to state
         if isinstance(default, list):
             state[name] = default[:]
-        elif getattr(default, '__call__', False):
+        elif callable(default):
             state[name] = None
         else:
             state[name] = default