diff -r 01dc11e7191f -r 1b0ef07ba783 mercurial/extensions.py
--- a/mercurial/extensions.py	Sat Jan 09 19:45:10 2016 +0900
+++ b/mercurial/extensions.py	Sat Jan 09 19:52:55 2016 +0900
@@ -286,7 +286,9 @@
 
     origfn = getattr(container, funcname)
     assert callable(origfn)
-    setattr(container, funcname, bind(wrapper, origfn))
+    wrap = bind(wrapper, origfn)
+    _updatewrapper(wrap, origfn)
+    setattr(container, funcname, wrap)
     return origfn
 
 def _disabledpaths(strip_init=False):