Comment 13 for bug 1825537

Reviewed: https://review.opendev.org/667155
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=e6c6178d22db43959103da1400017fa49b18f514
Submitter: Zuul
Branch: stable/stein

commit e6c6178d22db43959103da1400017fa49b18f514
Author: Matt Riedemann <email address hidden>
Date: Fri Apr 19 12:28:34 2019 -0400

    Drop source node allocations if finish_resize fails

    By the time finish_resize runs on the dest host, the instance
    host/node values are already pointing at the dest (they are
    set by resize_instance on the source compute before casting to
    finish_resize on the dest). If finish_resize fails, the instance
    is essentially stuck on the dest host so rather than revert the
    allocations (which will drop the new flavor allocations against
    the dest host where the instance now lives) we should just drop
    the old flavor allocations on the source node resource provider,
    which is what this change does.

    The functional regression recreate test is updated to show this
    working.

    Change-Id: I52c8d038118c858004e17e71b2fba9e9e2714815
    Closes-Bug: #1825537
    (cherry picked from commit ea297d6ffba81c5dc982afe6519de09ff3744cad)