title: Using pika connection.close() gives "WARNING:pika.adapters.base_connection:Unknown state on disconnect: 0"
body: <p>When closing a connection to RabbitMQ server using pika, the warning <code>WARNING:pika.adapters.base_connection:Unknown state on disconnect: 0</code> appears. </p>
  
  <p>If no <code>connection.close()</code> is used, the warning does not appear. What is causing this warning, and is this something we can ignore?</p>
  
  <p>Using Python 2.7, RabbitMQ 3.2.2, iPython 1.1.0, pika 0.9.13 on Mac OSX.</p>
  
  <p><img src="https://i.stack.imgur.com/cy8tg.png" alt="enter image description here"></p>