Describe the bug
When the celery worker executes openwisp_controller.connection.tasks.update_config, it incorrectly detects that another worker is executing the task, when in reality it is the same worker running it. As a result, the worker returns early, skipping the actual execution even though it is the correct one to run the task.

Steps To Reproduce
Steps to reproduce the behavior:

1. Change the configuration of device (e.g. change name or configuration)
2. Observe the log/output during the task's execution from the celery worker.
3. Notice that the task exits/returns early, incorrectly assuming another worker is executing it, despite being run by the current worker itself.

Expected behavior
The celery worker should correctly detect if another worker is running the task, and should proceed with execution when it is indeed the task's actual worker.