Comment 5 for bug 1781100

Reviewed: https://review.openstack.org/581741
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=246c61d82b6d2a4249cf2408268830dfbd71b8f6
Submitter: Zuul
Branch: stable/queens

commit 246c61d82b6d2a4249cf2408268830dfbd71b8f6
Author: Matt Riedemann <email address hidden>
Date: Tue Jul 10 22:11:05 2018 -0400

    Fix TypeError in prep_resize allocation cleanup

    The CachingScheduler doesn't create allocations in
    placement so when prep_resize fails and it tries
    to revert allocations, the _revert_allocation() method
    returns False and then prep_resize calls
    delete_allocation_for_failed_resize() which since change
    I7891b98f225f97ad47f189afb9110ef31c810717 has taken a
    context argument, but that's not being passed so it
    results in a TypeError.

    This fixes the TypeError and adds a functional test case
    which runs a resize reschedule scenario with the
    CachingScheduler.

    Change-Id: I0ec0c2d3f7ef8d2274b97a28a175d53921edc9db
    Closes-Bug: #1781100
    (cherry picked from commit 78af1de1587fb83e09d1c0639fb5a28eb6e51a27)