patch: fix extract() docstring, it returns branch as well stable

patch: fix extract() docstring, it returns branch as well

--- a/mercurial/patch.py	Thu Jul 22 14:33:50 2010 +0900
+++ b/mercurial/patch.py	Thu Jul 22 14:30:27 2010 +0900
@@ -174,7 +174,7 @@
 
     patch can be a normal patch or contained in an email message.
 
-    return tuple (filename, message, user, date, node, p1, p2).
+    return tuple (filename, message, user, date, branch, node, p1, p2).
     Any item in the returned tuple can be None. If filename is None,
     fileobj did not contain a patch. Caller must unlink filename when done.'''