Comment 1 for bug 1528620

problem is in check

file nailgun/db/sqlalchemy/fixman.py

        # Check if it's already uploaded
        obj_from_db = db().query(obj['model']).get(pk)
        if obj_from_db:
            logger.info("Fixture model '%s' with pk='%s' already"
                        " uploaded. Skipping", model_name, pk)
            continue

Existence of pk is not good way to check fixtures upload