bb310831b8
When un-assigning an Action, do not depend on the Dope Sheet space data `action` pointer. Instead, Blender now just sets the RNA property `id.animation_data.action = None` to un-assign the Action. Using RNA this way will ensure that the messagebus gets notified of this change as well. The Dope Sheet space data 'action' pointer is still set to `nullptr`, but it is now no longer used as primary way to clear the Action. Pull Request: https://projects.blender.org/blender/blender/pulls/129006