Comment 13 for bug 1628606

Reviewed: https://review.openstack.org/611093
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=28bc3c8221c6f12bd9f1dd6701026f389b1fc2f6
Submitter: Zuul
Branch: stable/pike

commit 28bc3c8221c6f12bd9f1dd6701026f389b1fc2f6
Author: Artom Lifshitz <email address hidden>
Date: Wed Oct 10 14:53:14 2018 -0400

    Handle volume API failure in _post_live_migration

    Previously, if the call to Cinder in _post_live_migration failed, the
    exception went unhandled and prevented us from calling
    post_live_migration_at_destination - which is where we set instance
    host and task state. This left the system in an inconsistent state,
    with the instance actually running on the destination, but
    with instance.host still set to the source. This patch simply wraps
    the Cinder API calls in a try/except, and logs the exception instead
    of blowing up. While "dumb", this has the virtue of being simple and
    minimizing potential side effects. A comprehensive refactoring of
    when, where and how we set instance host and task state to try to
    guarantee consistency is left as a TODO.

    Conflicts in nova/compute/manager.py due to absence of new Cinder flow
    conditional (and corresponding modifications to tests).

    Partial-bug: 1628606
    Change-Id: Icb0bdaf454935b3713c35339394d260b33520de5
    (cherry picked from commit 5513f48dea529fe4e690f50a462300129594210c)
    (cherry picked from commit cf3c2f391ad0f9d2a2d94247509bcb2709413e4f)
    (cherry picked from commit 53f9c8e5104076872021ed33e221e5526ca5059b)