util/ssh: stop keepalive in disconnect() when existing connection is used

SSHConnection does not open a new connection if an existing connection
is open. It reuses the connection and starts a keepalive command (cat).

On disconnect(), the keepalive command is only stopped for newly
initiated connections, not for existing ones. Fix that by stopping the
keepalive first, unconditionally.

Signed-off-by: Bastian Krause <bst@pengutronix.de>

Author: Bastian-Krause

labgrid/util/ssh.py

@@ -521,9 +521,10 @@ def _stop_keepalive(self):
     def disconnect(self):
         assert self._connected
         try:
+            self._stop_keepalive()
+
             if self._socket:
                 self._logger.info("Closing SSH connection to %s", self.host)
-                self._stop_keepalive()
                 self._stop_own_master()
         finally:
             self._connected = False