Updated openstack/openstack
Project: openstack/oslo.messaging  935b5bd5fa81421e08752e53bb178476d1efad25

rabbit: add some tests when rpc_backend is set

This change improves test coverage of the rabbit driver for new
value allowed in rpc_backend config option.

Change-Id: I52a8a8beb5b0d32647f52bb21abd5f7164dac2df