gevent.socket doesn't yield control when used to patch the underlying socket for a pubsub connection

[jpmelos]

Issue for further investigating #16, which shipped support for unpatched processes using gevent with an implementation that relies on gevent.select to detect when there's a new message in the pubsub channel. The original idea was the supprt that by replacing the underlying socket of the pubsub connection with a gevent.socket, so it would yield control to the event loop while waiting for a message in the pubsub channel.