Comment 8 for bug 1382190

To clarify what's happening with the rabbitmq charm: for its units to be
able cluster together, they need to refer to each other by hostname, see
[0] which was done based on the observed pattern as per #4,#7 comments above.

[0] https://code.launchpad.net/~jjo/charms/trusty/rabbitmq-server/fix-nodename-to-host-dns-PTR