Ensure to not call connectionClosed() twice.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1698 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/connection.py

@@ -305,6 +305,7 @@ class Connection(BaseConnection):
         return self.connector is not None and self.write_buf
 
     def _closure(self):
+        assert self.connector is not None, self.whoSetConnector()
         self.close()
         self.handler.connectionClosed(self)