There's no need for notify_closed() to take a 'conn' argument.

src/ZEO/zrpc/client.py

@@ -162,7 +162,7 @@ class ConnectionManager:
         self.connection = c
         self._thread = None
 
-    def notify_closed(self, conn):
+    def notify_closed(self):
         self.connected = 0
         self.connection = None
         self.client.notifyDisconnected()

src/ZEO/zrpc/connection.py

@@ -462,4 +462,4 @@ class ManagedConnection(Connection):
 
     def close(self):
         self.__super_close()
-        self.__mgr.notify_closed(self)
+        self.__mgr.notify_closed()