tripleoclient could hang forever if execution fails without sending an error message

[James Slagle]

Most of the workflows modules in tripleoclient use the pattern of blocking on base.wait_for_messages to determine when a mistral execution has finished. wait_for_messages will check if an error has happened only by checking the status in the returned payload.

However, there are other circumstances where the execution could fail without sending back any messages which could cause tripleoclient to block forever. These include syntax errors, action name mispellings, import errors, etc.

All these types of errors cause mistral to just fail the exception with no message sent back on the queue.

[Luke Short (ekultails)]

Closing as this is addressed in master (we no longer use Mistral).