Comment 13 for bug 1764883

Reviewed: https://review.openstack.org/621205
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1abdb4ca22436c5eabadeab46b1237154c9cca92
Submitter: Zuul
Branch: stable/pike

commit 1abdb4ca22436c5eabadeab46b1237154c9cca92
Author: Lee Yarwood <email address hidden>
Date: Wed Apr 18 14:35:07 2018 +0100

    compute: Ensure pre-migrating instances are destroyed during init_host

    Previously _destroy_evacuated_instances would not remove instances
    associated with evacuation migration records in a pre-migrating state.
    This could lead to a race between the original source host and the new
    destination if the source returned early, calling init_instance during
    the evacuation process.

    This change now includes pre-migrating migration records when looking
    for active evacuations. Additionally the dict of evacuating instances is
    then returned to init_host and used to skip running init_instance
    against such instances ensuring no race occurs between the two computes.

    NOTE(lyarwood): Conflict due to edeeaf9102eccb78f1a2555c7e18c3d706f07639
    not being present in stable/pike.

    Conflicts:
            nova/tests/functional/regressions/test_bug_1764883.py

    Closes-bug: #1764883
    Change-Id: I379678dfdb2609f12a572d4f99c8e9da4deab803
    (cherry picked from commit c4988cdabf311d29cf64af732091068cfabeedaa)
    (cherry picked from commit 8bba879141d644b248d246cb2ed196068e20785c)