This is a partial backport of Iea6288fe6d341ee92f87a35e0b0a59fe564ab96c
a change introduced in Stein that fixed OS detection in the
nova-live-migration job while installing Ceph.
This is required after the devstack-plugin-ceph job was recently
refactored by I51c90e592070b99422e692d5e9e97083d93146e8 and in doing so
introduced various OS specific conditionals that require os_CODENAME to
(cherry picked from commit