Comment 6 for bug 1763051

Reviewed: https://review.openstack.org/612714
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ae2da62955e5c856fec71eebb4f3458fb4c7fb79
Submitter: Zuul
Branch: stable/rocky

commit ae2da62955e5c856fec71eebb4f3458fb4c7fb79
Author: Matt Riedemann <email address hidden>
Date: Mon Oct 15 18:16:40 2018 -0400

    Move live_migration.pre.start to the start of the method

    This simply moves the pre_live_migration start notification
    back to the start of the method before creating new volume
    attachments. While in here, the list of bdms are passed to
    the notify_about_instance_action method so if
    [notifications]/bdms_in_notifications is True we don't have
    to pull them out of the database again for each versioned
    notification.

    Change-Id: I372eddb9e356b02328f937917a856bc631691f53
    Partial-Bug: #1763051
    (cherry picked from commit 7a2228142b8f8f015a554e2b25198ab37811a058)