Comment 8 for bug 1258256

Reviewed: https://review.openstack.org/62454
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=81af1ab488930b511cac056cdc4ac2a8a26f0d7b
Submitter: Jenkins
Branch: stable/havana

commit 81af1ab488930b511cac056cdc4ac2a8a26f0d7b
Author: Dan Smith <email address hidden>
Date: Mon Dec 2 12:25:04 2013 -0800

    Make Serializer able to backlevel objects

    This improves handling the situation where nova-api sends newer
    objects to an older compute node. In this case, the serializer detects
    the IncompatibleObjectVersion error and asks conductor to backlevel it.
    This means we call into the conductor with the primitive object that we
    can't handle, and basically ask it to hydrate it and call
    obj_make_compatible() on our behalf and pass it back to us.

    This eliminates the need for API to know whether it's talking to
    an older compute and allows a newer conductor to assist older
    compute nodes during upgrades to a significant degree.

    Adapted for havana/stable from master commit: 0eb7e35

    Related-Bug: #1258256
    Change-Id: I4b17c8382619e4f73b83c026bf68549ac67a68a2