When Mistral workflows execute a second workflow (a sub-workflow
execution), the parent workflow can't easily determine if sub-workflow
failed. This is because the failure is communicated via a Zaqar message
only and when a workflow ends with a successful Zaqar message it appears
have been successful. This problem surfaces because parent workflows
should have an "on-error" attribute but it is never called, as the
workflow doesn't error.
This change marks the workflow as failed if the message has the status
"FAILED". Now when a sub-workflow fails, the task that called it should
have the on-error triggered. Previously it would always go to
on-success.
Change-Id: Ic1781bcf3922da61d42970cf2b42c951f83f7a74
Related-Bug: #1651704
12f734562c