3baf6c14a5
The PR's guard used `(job.get('schedule') or {}).get('kind')` which
crashes with AttributeError when schedule is a raw string (e.g.
'every 5m'), as happens in test_parallel_pool.py fixtures and any
job created via create_job(schedule='every 1h'). Use the
isinstance guard pattern already used at lines 5181 and 5325.