title: Messages with expiration are not removed from RabbitMQ
body: <p>I am sending a normal message through a producer to RabbitMQ and then I send a second message with the <code>expiration</code> attribute assigned to a value. Then using the <code>rabbitmqctl list_queues</code> command I monitor the status of the messages.</p>
  
  <p>I found that if I send a normal message first and then a message with <code>expiration</code>, the <code>rabbitmqctl list_queues</code> is always showing me 2 messages pending on the queue. When I consume them, I get only one.</p>
  
  <p>On the other hand if I send just 1 message with <code>expiration</code>, in the beginning I see the message and then after the correct expiration time, I find it deleted.</p>
  
  <p>My question is, on the first situation is actually the message taking space? Or it is an interface bug?</p>
  
  <p>My rabbitMQ version is:
  <code>rabbitmq-server.noarch -&gt; 3.1.5-1.el6</code></p>