title: celery missed heartbeat (on_node_lost)
body: <p>I just upgraded to celery 3.1 and now I see this i my logs ::</p>
  
  <pre><code>on_node_lost - INFO - missed heartbeat from celery@queue_name for every queue/worker in my cluster.
  </code></pre>
  
  <p>According to the docs <code>BROKER_HEARTBEAT</code> is off by default and I haven't configured it.</p>
  
  <p>Should I explicitly set <code>BROKER_HEARTBEAT=0</code> or is there something else that I should be checking?</p>