diff -r 7e9a15fa6c8f -r 5751631246de mercurial/extensions.py
--- a/mercurial/extensions.py	Tue Nov 18 15:35:34 2008 -0600
+++ b/mercurial/extensions.py	Tue Nov 18 16:02:14 2008 -0600
@@ -96,7 +96,8 @@
 
     origfn = entry[0]
     def wrap(*args, **kwargs):
-        return wrapper(origfn, *args, **kwargs)
+        return util.checksignature(wrapper)(
+            util.checksignature(origfn), *args, **kwargs)
 
     wrap.__doc__ = getattr(origfn, '__doc__')
     wrap.__module__ = getattr(origfn, '__module__')