The logic within the pre_tasks was too loose. The pre_tasks need
to have a bit more restrictive conditionals. Additionall the
`lxc-device add` command which is being used always exits 0
even when the device add fails. While the task does not have
issues with running we should be making sure that our changes
are being recoreded correctly.
Closes-Bug: 1434945
Change-Id: Icb1707db6bde6c0a26af6bca21a1f88dc3c315a8