title: Running airflow worker gives error: Address already in use
body: <p>I am running Airflow with CeleryExecutor. I am able to run the commands <code>airflow webserver</code> and <code>airflow scheduler</code> but trying to run <code>airflow worker</code> gives the error: <strong>socket.error: [Errno 98] Address already in use</strong>.</p>
  
  <p>The traceback:
  <a href="https://i.stack.imgur.com/9QJEQ.png" rel="noreferrer"><img src="https://i.stack.imgur.com/9QJEQ.png" alt="enter image description here"></a></p>