Allows nodes with a single IP stack to be deployed from a dual-stack
Ironic.
Detecting advertised address and usable Ironic URLs are done completely
independently which does open some space for a misconfiguration. I hope
it's not likely in the reality, especially since this feature is
targetting advanced standalone users.
Change-Id: Ifa506c58caebe00b37167d329b81c166cdb323f2
Closes-Bug: #2045548