Comment 5 for bug 1292589

Sergio - the 2 messages thing in being addressed in another bug https://bugs.launchpad.net/horizon/+bug/1278353

I believe the nova API has been intentionally removed. See the link I put into the initial description for the email discussion, plus especially this change:
https://github.com/openstack/nova/commit/1b15b23b0a629e00913a40c5def42e5ca887071c