We have always accepted server patches via the mailing list: https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq...

But it's true that the community has been much more involved in clients like Pika, for example.

And yes we are planning to open up the bug tracker.

A piece of advice for anyone doing an open source project - start with an open tracker, because opening up a previously closed tracker is a royal pain in the butt.