Comment 2 for bug 1697389

Reviewed: https://review.openstack.org/475590
Committed: https://git.openstack.org/cgit/openstack/os-win/commit/?id=938a99a7a7b1f55b7e31f0ff028d4f72ee0e2cdb
Submitter: Jenkins
Branch: stable/ocata

commit 938a99a7a7b1f55b7e31f0ff028d4f72ee0e2cdb
Author: Claudiu Belu <email address hidden>
Date: Tue Jun 13 16:07:58 2017 +0300

    Fixes cached old WMI service objects issue

    When using WMI, the resources passed to the
    Msvm_VirtualSystemManagementService are not cleaned up
    by the garbage collector if the Service object is still
    referenced (cached as a property in BaseUtilsVirt).

    PyMI doesn't have this issue, so the Service objects can be
    safely cached.

    This issue only affects Windows / Hyper-V Server 2012.

    Conflicts:
            os_win/tests/unit/utils/compute/test_migrationutils.py

    Closes-Bug: #1697389
    (cherry picked from commit 49a012e83c44d28ee533aace22c42b1781b8e5e2)

    tests: Sets baseutils.BaseUtilsVirt._old_wmi

    There is a race condition between tests, and because
    the _old_wmi is not set, it will try to load it, but since it
    is mocked, it cannot, and it shouldn't.

    Change-Id: Id029baf2e72f7b67eb6af3b3e66f998b902fd412

    Change-Id: If8df0bf0a2f13a9e94993dde8b2a18943f2e9f83