You're referring to the old style of how Celery passes parameters into tasks, that was prone to failures and has been deprecated in Celery 3.x. From http://docs.celeryproject.org/en/2.5/changelog.html#v220-important:

> The magic keyword arguments were responsibile for many problems and quirks: notably issues with tasks and decorators, and name collisions in keyword arguments for the unaware.

> It wasn’t easy to find a way to deprecate the magic keyword arguments, but we think this is a solution that makes sense and it will not have any adverse effects for existing code.

The new tasks now have all the magic keywords attached to the task function if needed. Regarding the deprecation:

> Similarly, the task.accept_magic_kwargs attribute will no longer have any effect starting from version 3.0.

Specifically the `index_objects` task here doesn't need key value arguments anyways.