Comment 4 for bug 1727260

Reviewed: https://review.openstack.org/546655
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=d6a072b5c5a3ff9de7f4b42cda517ead17efe561
Submitter: Zuul
Branch: stable/queens

commit d6a072b5c5a3ff9de7f4b42cda517ead17efe561
Author: Sahid Orentino Ferdjaoui <email address hidden>
Date: Wed Oct 25 05:57:11 2017 -0400

    libvirt: disconnect volume from host during detach

    Under certain failure scenarios it may be that although the libvirt
    definition for the volume has been removed for the instance that the
    associated storage lun on the compute server may not have been fully
    cleaned up yet.

    In case users try an other attempt to detach volume we should not stop
    the process whether the device is not found in domain definition but
    try to disconnect the logical device from host.

    This commit makes the process to attempt a disconnect volume even if
    the device is not attached to the guest.

    Closes-Bug: #1727260
    Change-Id: I4182642aab3fd2ffb1c97d2de9bdca58982289d8
    Signed-off-by: Sahid Orentino Ferdjaoui <email address hidden>
    (cherry picked from commit ce531dd1b763704b9043ddde8e80ac99cd193660)