Comment 9 for bug 1771860

Reviewed: https://review.opendev.org/647630
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d6832b0e070cebbe48a71a46d88b9412375989c1
Submitter: Zuul
Branch: stable/pike

commit d6832b0e070cebbe48a71a46d88b9412375989c1
Author: Matt Riedemann <email address hidden>
Date: Thu May 10 19:27:36 2018 -0400

    Update instance.availability_zone during live migration

    While triaging bug 1768876 there was some concern
    that change I8d426f2635232ffc4b510548a905794ca88d7f99
    in Pike had regressed some behavior where a user that
    does not explicitly request a specific AZ during server
    create is then later restricted to only move operations
    within that same AZ.

    This test shows that is not a regression because the
    AvailabilityZoneFilter looks at RequestSpec.availability_zone
    rather than instance.availabililty_zone, so the instance
    is free to be moved across zones.

    As a result of the test, however, it was noticed that
    the instance.availability_zone isn't updated during live
    migration once the destination host is selected. The other
    move operations like unshelve, evacuate and cold migrate
    all update the instance.availabiltiy_zone, so this copies
    the same logic.

    Conflicts:
          nova/conductor/tasks/live_migrate.py
          nova/tests/unit/conductor/tasks/test_live_migrate.py

    NOTE(mriedem): The conflicts were due to changes
    Idad5cdbb2c5647c469e4ad5e9393564255df0f7f and
    I9068a5a5b47cef565802a6d58f37777464644100 in Queens.
    The _wait_for_migration_status interface also changed
    with I752617066bb2167b49239ab9d17b0c89754a3e12 in Queens.

    Change-Id: I9f73c237923fdcbf4096edc5aedd2c968d4b893e
    Closes-Bug: #1771860
    Related-Bug: #1768876
    (cherry picked from commit 0ed68c76fa8a84d1d5f0ab945e34c8e16341d627)
    (cherry picked from commit 133763d3582c2e85e4e5962b542294135d1a7f4c)
    (cherry picked from commit ee07c1c67d4ee6b146783c40826c4a28bd7367c3)