Comment 7 for bug 1914747

Reviewed: https://review.opendev.org/c/openstack/neutron/+/775103
Committed: https://opendev.org/openstack/neutron/commit/d570871e57f6d65c1eedad902754aa098a942829
Submitter: "Zuul (22348)"
Branch: stable/rocky

commit d570871e57f6d65c1eedad902754aa098a942829
Author: Slawek Kaplonski <email address hidden>
Date: Fri Feb 5 13:32:23 2021 +0100

    Fix update of trunk subports during live migration

    During the live migration trunk subports where updated only based
    on the "host_id" field. But when rpc message to update subports
    is send trunk's port is still bound to the old host and has
    "migrating_to" field in binding:profile set to the new host.
    Because of that binding:host_id for the subport's port wasn't updated
    proberly and port was set to DOWN on the new host.
    That could even cause connectivity break if L2population is used in the
    cloud.

    This patch fixes that by updating subport's binding:host_id field based
    on the migrating_to field if that is available and not empty.

    Closes-Bug: #1914747
    Change-Id: I98e55242d381ada642ca0729e9aefdea7628c945
    (cherry picked from commit e05101c8ac953cc2823b35aaed3d499afc101988)