error: playbook openwisp2_firmware_upgrader: false, but supervisorctl", "restart", "celery_firmware_upgrader runs and fails

[emsu-io-suefke]

At commit b2c6431 + some unrelated local changes regarding creation of SSL certificates:
Attached playbook.yml has been stripped of any personal information by placing , hostname of of target replaced by <target_host>. Hopefully this is enough to re-create the problem. To create a minimal working example,
set vars:
openwisp2_firmware_upgrader: false
for any configuration that works otherwise.

In the attached log of the ansible run, in line 466, the Task "Template for supervisor celery firmware_upgrader" is skipped,
but in line 546 the Task "Restart other supervisor managed services" runs on <celery_firmware_upgrader> and fails.

Expected behavior:
When openwisp2_firmware_upgrader == false, supervisor template 'celery_firmware_upgrader' is left alone or (better yet) stopped if found running but nothing else happens.
playbook.yml-cleaned.txt
openwisp-ansible-issue.log