sshrepo: fix addchangegroup's signature

Make it mirror the usage found in localrepo.push. This should only
affect pushes to pre-unbundle ssh servers.

mercurial/sshrepo.py

@@ -186,7 +186,7 b' class sshrepository(wireproto.wirereposi'
     def unlock(self):
         self._call("unlock")
 
-    def addchangegroup(self, cg, source, url):
+    def addchangegroup(self, cg, source, url, lock=None):
         '''Send a changegroup to the remote server.  Return an integer
         similar to unbundle(). DEPRECATED, since it requires locking the
         remote.'''