Comment 4 for bug 1850280

Reviewed: https://review.opendev.org/694018
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=4cb493fe4f79e736ae4fd7874b02d1d5ceed02c1
Submitter: Zuul
Branch: stable/train

commit 4cb493fe4f79e736ae4fd7874b02d1d5ceed02c1
Author: Balazs Gibizer <email address hidden>
Date: Tue Oct 29 16:43:04 2019 +0100

    Use admin neutron client to see if instance has qos ports

    The nova-api checks at each move* operation if the instance has qos port
    attached as not all the move operations are supported for such servers.
    Nova uses the request context to initialize the neutron client for the
    port query. However neutron does not return the value of the
    resource_request of the port if it is queried with a non admin client.
    This causes that if the move operation is initiated by a non admin
    then nova thinks that the ports do not have resource request.

    This patch creates an admin context for this neutron query.

    The new functional tests are not added before this patch in a regression
    test like way as existing functional tests are reused with different
    setup and doing that without the fix causes a lot of different failure
    scenarios.

    Note that neutron fixture is changed to simulate the different behavior
    in case of different request context are used to initialize the client.

    *: Note that Id5f2f4f22b856c989e2eef8ed56b9829d1bcefb6 removed the check
       for evacuate in Ussuri but exists in Train and Stein.

    Conflicts:
          nova/tests/fixtures.py
    Due to d2d4317e1a31f6ac40c5f29b57cd4ea196dc8780 is missing from
    stable/train

    Another difference from the original patch is in
    nova/api/openstack/compute/evacuate.py due to
    Id5f2f4f22b856c989e2eef8ed56b9829d1bcefb6 is only merged in Ussuri.

    Change-Id: I3cf6eb4654663865d9258c38f05cd05974ffcf9d
    Closes-Bug: #1850280
    (cherry picked from commit 899976960503524b8e5c6588e339742ca4bf8158)