[AIRFLOW-6820] fixup! fix unbound variable
[AIRFLOW-6820] fixup! fix unbound variable

(cherry picked from commit a54cf8b33030a52c45e46cf7f507f496ee00d610)

owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow