Comment 2 for bug 1768927

Reviewed: https://review.openstack.org/566143
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=3437baedf646c7cd3da43440368edc194a880db8
Submitter: Zuul
Branch: master

commit 3437baedf646c7cd3da43440368edc194a880db8
Author: Matt Riedemann <email address hidden>
Date: Thu May 3 15:00:02 2018 -0400

    Fix being able to hard reboot a pausing instance

    The allowed task states for a hard reboot include 'pausing'
    but the instance.save(expected_task_states) doesn't include
    'pausing', so if you try to hard reboot a pausing instance
    it will fail with UnexpectedTaskStateError.

    This makes the expected_task_states passed to Instance.save
    use the same list of allowed task states that we use in the
    check_instance_state decorator, and re-writes the unit test
    to use an actual database to verify the Instance.save()
    behavior and task state check in the DB API.

    While we're at it, the API reference is updated to indicate
    the allowed states for each type of reboot.

    Change-Id: I5a21350e48a637e581d269fb567bb96c1899e174
    Closes-Bug: #1768927