Get rid of last use of _rpc_mgr[0][1] to get the server address in the

test suite.  The address is now found as the _addr attribute of the
client storage instance.

src/ZEO/tests/CommitLockTests.py

@@ -185,7 +185,7 @@ def _duplicate_client(self):
         # The rpc mgr addr attribute is a list.  Each element in the
         # list is a socket domain (AF_INET, AF_UNIX, etc.) and an
         # address.
-        addr = self._storage._rpc_mgr.addr[0][1]
+        addr = self._storage._addr
         new = ZEO.ClientStorage.ClientStorage(addr, wait=1)
         new.registerDB(DummyDB(), None)
         return new