Comment 4 for bug 1817542

Reviewed: https://review.openstack.org/641173
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=e2185168f812286dd140936df64261e67568a410
Submitter: Zuul
Branch: stable/rocky

commit e2185168f812286dd140936df64261e67568a410
Author: Takashi NATSUME <email address hidden>
Date: Thu Feb 28 13:49:41 2019 +0900

    Fix an error when generating a host ID

    When instance action events are created by periodic tasks,
    the project IDs of them become null (None).
    It causes an error when 'hostId' is generated
    in the "Show Server Action Details"
    (GET /servers/{server_id}/os-instance-actions/{request_id})
    API.

    Fix the issue by using the project ID of the server
    if the project ID of the event is None.

    Conflicts:
        nova/tests/unit/api/openstack/compute/test_instance_actions.py

        The conflicts are due to not having the following
        changes in Rocky.

        I7f5f08691ca3f73073c66c29dddb996fb2c2b266
        If91c179e3823c8b0da744a9363906b0f7b05c326
        I44546bc9798708a48a250cc3a21bdbcabe2649e1

    Change-Id: Iac07fcddd4cc3321c6efe702066eb8af6a875418
    Closes-Bug: #1817542
    (cherry picked from commit 31fe7c76009e1c6d7859036e44b057d081b059b5)