Retrying step in workflow creates new RT ticket

[michamos]

Expected Behavior

Retrying a step in the workflow would retry only the last step.

Current Behavior

The workflow restarts, creating a second RT ticket, and sending a new email out to the submitter.

Steps to Reproduce (for bugs)

1. Make a submission
2. Retry step in the halted workflow

[michamos]

The repeated failures with DestinationExistsError: Destination exists: /opt/inspire/var/data/workflows as in https://labs.inspirehep.net/holdingpen/670018#errors make this very annoying