Comment 9 for bug 1741125

Reviewed: https://review.openstack.org/531022
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=db711bc06fcc234488b107dd22dd2a0272939174
Submitter: Zuul
Branch: master

commit db711bc06fcc234488b107dd22dd2a0272939174
Author: Ed Leafe <email address hidden>
Date: Wed Jan 3 21:38:43 2018 +0000

    Fix race condition in retrying migrations

    During testing in the alternate host series, it was found that retries
    when resizing an instance would always fail. This turned out to be true
    even before alternate hosts for resize was introduced. Further
    investigation showed that there was a race in call to retry the resize
    and the revert of the original attempt.

    This patch fixes that race condition, and updates the regression test to
    reflect the correct results.

    Blueprint: return-alternate-hosts

    Closes-Bug #1741125

    Change-Id: I12b4e1d9e50fefd81128df85d75bb34564f9da2c