Comment 14 for bug 1750618

Reviewed: https://review.openstack.org/550560
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=286dd2c23c7c361c6538be65941e3c19e83e6d52
Submitter: Zuul
Branch: stable/ocata

commit 286dd2c23c7c361c6538be65941e3c19e83e6d52
Author: Matt Riedemann <email address hidden>
Date: Tue Feb 20 13:48:12 2018 -0500

    Only attempt a rebuild claim for an evacuation to a new host

    Change I11746d1ea996a0f18b7c54b4c9c21df58cc4714b changed the
    behavior of the API and conductor when rebuilding an instance
    with a new image such that the image is run through the scheduler
    filters again to see if it will work on the existing host that
    the instance is running on.

    As a result, conductor started passing 'scheduled_node' to the
    compute which was using it for logic to tell if a claim should be
    attempted. We don't need to do a claim for a rebuild since we're
    on the same host.

    This removes the scheduled_node logic from the claim code, as we
    should only ever attempt a claim if we're evacuating, which we
    can determine based on the 'recreate' parameter.

    Conflicts:
          nova/tests/functional/test_servers.py

    NOTE(mriedem): test_rebuild_with_new_image does not exist in
    Ocata and does not apply to Ocata since it is primarily
    testing allocations getting created in Placement via the
    FilterScheduler, which was new in Pike. As a result the change
    to that test is not part of this backport, but a similar assertion
    is added to an existing rebuild unit test.

    Change-Id: I7fde8ce9dea16679e76b0cb2db1427aeeec0c222
    Closes-Bug: #1750618
    (cherry picked from commit a39029076c7997236a7f999682fb1e998c474204)
    (cherry picked from commit 3c5e519a8875a9766a0d3a06cb76cceba26634e6)
    (cherry picked from commit 9890f3f69622489a0fd57cb1df354d7aa60161e0)