Comment 13 for bug 1825034

I know I am too late to the party here but just thought of leaving a comment here:

Agreed we don't have many great ways of fixing this particular bug (I would have preferred hard delete of the marker too - but then this would still be racy until the time the whole migration is complete since each cell would have a marker) but on a more general note maybe we should add something to the upgrade status checker that would delete persistent markers once it deems the migration complete. We had a similar issues where we had to use objects.RequestSpec.get_by_instance_uuid() for a script and this blew up for the request_spec marker (which had a uuid instead of a JSON blob as the spec) that was left out since one of the migrations in newton.