Recover from deleting state on compute manager start-up

[David McNally]

If a compute manager is stopped / fails during a delete operation then the instance will be left stuck with task_state=deleting

It should be possible to treat instances in this state as if they have failed to delete correctly and we can trigger the delete again when the compute manager restarts.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/55135

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/55660
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=0252d0981af9daaf9370a50c28d8baf4a9d29619
Submitter: Jenkins
Branch: master

commit 0252d0981af9daaf9370a50c28d8baf4a9d29619
Author: Stanislaw Pitucha <email address hidden>
Date: Fri Nov 8 13:38:08 2013 +0000

    Cleanup 'deleting' instances on restart

    In case some instance was marked as deleting but for some reason didn't
    finish (for example request was stuck in libvirt), retry the delete at
    startup. This happens at startup and on the host owning the instance,
    so there's no reason to use the lock.

    Change-Id: Iad18e9a7c6cb8e272e67a82284127ad895441dcf
    Partial-Bug: #1248563
    Closes-Bug: 1247174
    Implements: blueprint recover-stuck-state