Comment 8 for bug 1826375

Reviewed: https://review.opendev.org/656966
Committed: https://git.openstack.org/cgit/openstack/tripleo-heat-templates/commit/?id=a8ec69941657975fe6a2b8616c3c729013a30dff
Submitter: Zuul
Branch: master

commit a8ec69941657975fe6a2b8616c3c729013a30dff
Author: Jose Luis Franco Arza <email address hidden>
Date: Fri May 3 17:33:54 2019 +0200

    Clean up leftover mount point after docker stop.

    Some mountpoints are left on the host after docker shut down. This
    seems to be an issue with docker, but couldn't trace it back to a
    specific docker bug.

    In the meantime to unblock the upgrade CI we make sure that every
    mount point under /var/lib/docker are umounted before deleting that
    directory.

    Note that we need to keep the order right, so that we do a depth first
    list so that umount can do leaves before root.

    Closes-Bug: #1826375
    Co-Authored-By: Sofer Athlan-Guyot <email address hidden>

    Change-Id: I03a065556caca4385bb8b28be0dfbe21addbf003