the value returned from "Pwwka::Receiver.subscribe" is unusable when supplied "block: false" argument

[laser]

Problem

The Pwwka::Receiver.subscribe class method creates a new Pwwka::Receiver which executed the provided handler once per message delivered to a queue (which it creates) bound to each routing key in the routing_key argument. If the block: false argument is provided, the Bunny subscription should be created in a non-blocking fashion, i.e. the call to Bunny::Queue#subscribe should return immediately, and the Pwwka::Receiver should be returned.

Unfortunately, the Pwwka::Receiver.subscribe's ensure block closes the underlying connection before the receiver is returned, rendering the receiver unusable.