Comment 57 for bug 1404867

Reviewed: https://review.openstack.org/546277
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=c1b3d8c2140197dca2d7037476953cc46cbae793
Submitter: Zuul
Branch: stable/queens

commit c1b3d8c2140197dca2d7037476953cc46cbae793
Author: Matt Riedemann <email address hidden>
Date: Thu Feb 15 16:33:56 2018 -0500

    Detach volumes when deleting a BFV server pre-scheduling

    If the user creates a volume-backed server from an existing
    volume, the API reserves the volume by creating an attachment
    against it. This puts the volume into 'attaching' status.

    If the user then deletes the server before it's created in a
    cell, by deleting the build request, the attached volume is
    orphaned and requires admin intervention in the block storage
    service.

    This change simply pulls the BDMs off the BuildRequest when
    we delete the server via the build request and does the same
    local cleanup of those volumes as we would in a "normal" local
    delete scenario that the instance was created in a cell but
    doesn't have a host.

    We don't have to worry about ports in this scenario since
    ports are created on the compute, in a cell, and if we're
    deleting a build request then we never got far enough to
    create ports.

    Change-Id: I1a576bdb16befabe06a9728d7adf008fc0667077
    Partial-Bug: #1404867
    (cherry picked from commit 0652e4ab3d506ea21f1bd80b6802c6df5e7b523e)