I'm concerned about this change.  If you go up the callstack, this is called when [retrieving the submission to assess](https://github.com/edx/edx-ora2/blob/master/apps/openassessment/assessment/peer_api.py#L503).  Presumably if we've already started an assessment, we'd like to continue working on that assessment (the same `PeerWorkflowItem`, not a duplicate) the next time we load the page.  Am I misreading this?