Comment 10 for bug 1551703

Reviewed: https://review.opendev.org/696085
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=f3763778dd59c78f68bedd124c653b6744acbc9c
Submitter: Zuul
Branch: stable/train

commit f3763778dd59c78f68bedd124c653b6744acbc9c
Author: Matt Riedemann <email address hidden>
Date: Tue Oct 29 12:10:08 2019 -0400

    Reset instance to current vm_state if rolling back in resize_instance

    You can resize a stopped instance and if the compute driver raises
    InstanceFaultRollback from migrate_disk_and_power_off, the
    _error_out_instance_on_exception decorator, used in the _resize_instance
    method, will by default reset the instance vm_state to ACTIVE even though
    the guest is stopped. The driver could raise InstanceFaultRollback if you
    try resizing the root disk down on a non-volume-backed instance.

    This builds on [1] and does the same thing as prep_resize [2] for
    making sure the original vm_state is reset on InstanceFaultRollback.

    [1] Ie4f9177f4d54cbc7dbcf58bd107fd5f24c60d8bb
    [2] I17543ecb572934ecc7d0bbc7a4ad2f537fa499bc

    Change-Id: Iff1f9f28a1e4ecf00368cbcac27b7687a5eb0dcf
    Closes-Bug: #1551703
    (cherry picked from commit 5a20996405c5788855a2457283bbbe7d78140a9c)