codereview: restore help messages

Docstrings were not being set for the wrapper
functions returned by the hgcommand decorator.

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6059043

lib/codereview/codereview.py

@@ -1263,6 +1263,7 @@ def hgcommand(f):
 		if not err:
 			return 0
 		raise hg_util.Abort(err)
+	wrapped.__doc__ = f.__doc__
 	return wrapped
 
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