Comment 2 for bug 1786318

Reviewed: https://review.openstack.org/590439
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=3a4b4b91b0bee514d47a67f6a5f9c4ab9ae7f7d8
Submitter: Zuul
Branch: master

commit 3a4b4b91b0bee514d47a67f6a5f9c4ab9ae7f7d8
Author: Lee Yarwood <email address hidden>
Date: Thu Aug 9 17:43:50 2018 +0100

    block_device: Rollback volumes to in-use on DeviceDetachFailed

    The call to os-roll_detaching was dropped when
    I3800b466a50b1e5f5d1e8c8a963d9a6258af67ee started to catch and reraise
    DeviceDetachFailed. This call is required to ensure a volume returns to
    an in-use state when the instance is unable to detach.

    Closes-Bug: #1786318
    Change-Id: I6b3dc09acc6f360806ce0ef8c8a65addbf4a8c51