IntegrityError when creating new workers or revisions via manage.py load_export

New workers or new revisions created by load_export fail because the .get_or_create does not have a repo_id available when falling back to a creation.

Worker version creation failed: null value in column "repo_id" violates not-null constraint
DETAIL:  Failing row contains (25ba418f-0e52-4c08-b890-5560ac4adccc, 804693d5800c205edade315ed3585ea594f30325, Fake revision, Rouchet+Admin, null, 2022-01-24 15:59:13.681774+00, 2022-01-24 15:59:13.681798+00).