Hi,
I pushed a proposed workaround for the rabbitmq problem running devstack on Fedora 20.
Ideally it would be best to fix the problem with rabbitmq, but in the meantime this change
shouldn't hurt anything when rabbit behaves and it made devstack complete successfully
again for me on the first try.
https://review.openstack.org/#/c/70156/
Let me know if you have any feedback. Thanks.
-Ben