Properly mark a backup as FAILED if the process failed

* Add a try except around the backup runner
* Moved conductor update calls outside of the scope of
  the runner with statement to catch exceptions in
  the __exit__ method.

Closes-Bug: #1256384

Change-Id: Icf539ab75314476b42a6e175c087ff61cc3608e1
Merge "Properly mark a backup as FAILED if the process failed"