When a new Action slot is created by keying a property, it is now
named after the last-assigned slot. This is in support of the
following scenario:
- Action `A` is assigned, with slot `Legacy Slot`.
- The slot is renamed to `Main Light`, because that's what being
animated by it.
- Animator wants to try an alternative animation, and unassigns the
Action.
- Animator starts keying the light, which creates Action `B` and a
slot.
- This slot is now also named `Main Light`, independently of the
actual name of the light being animated.
- Animator can switch between actions `A` and `B`, and because the
slots have the same name, the auto-assignment Just Works™.
Pull Request: https://projects.blender.org/blender/blender/pulls/131600
e909a17554