Comment 33 for bug 1781286

Reviewed: https://review.opendev.org/686050
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ac85b76178017b4bda30502a6ebb9c990435ec72
Submitter: Zuul
Branch: master

commit ac85b76178017b4bda30502a6ebb9c990435ec72
Author: Matt Riedemann <email address hidden>
Date: Tue Oct 1 17:30:54 2019 -0400

    Set Instance AZ from Selection AZ during migrate reschedule

    This builds on change Ia50c5f4dd2204f1cafa669097d1e744479c4d8c8
    to use the Selection.availability_zone value when rescheduling
    during a resize or cold migrate so that the cell conductor does not
    have to make an up-call to the aggregates table in the API DB
    which will fail if the cell conductor is not configured to use
    the API DB.

    The functional test added in Ic6926eecda1f9dd7183d66c67f04f308f6a1799d
    is updated to show the failure is gone and we get the AZ from the
    Selection object during the reschedule.

    For the case that the availability_zone field is not in the Selection
    object, there are existing unit tests in
    nova.tests.unit.conductor.tasks.test_migrate which will make sure we
    are not unconditionally trying to access the Selection.availability_zone
    field.

    Change-Id: I103d5023d3a3a7c367c7eea7fb103cb8ec52accf
    Closes-Bug: #1781286