Defer image_ref update to manager on rebuild
Defer image_ref update to manager on rebuild

We shouldn't update the DB and use it for passing the new image_ref for
a rebuild.  This causes a usage exists notification for the new image
instead of the old... and technically the new image is not accurate
until we shutdown the old instance and try building the new one..

Fixes bug 997245

Change-Id: Ia4bd4b8af90080a11875d9ee56661286bc3f5593

citrix-openstack-build/oslo.versionedobjects,openstack/oslo.versionedobjects