Attribute not updated when animated with `.animate`

[hydrobeam]

Description of bug / unexpected behavior

Mobject attributes are not updated when animated with .animate, but are successfully changed when done outside of animations

Expected behavior

The attribute should be updated.

How to reproduce the issue

class TS(Scene):
    def construct(self):
        c1 = Circle(fill_color=BLUE, fill_opacity=1)

        c1.set_stroke(PURPLE)
        # stroke is changed here, then becomes white 
        c1.set_stroke(WHITE)

        self.add(c1)
        self.play(c1.animate.set_stroke(color=RED)) # visually becomes red, but attribute does not match

        if c1.stroke_color == RED: # stroke_color  attr is `WHITE` not `RED`, so nothing is animated.
            a = Rectangle().to_edge(UP)
            self.play(DrawBorderThenFill(a))
        
        breakpoint()

Additional comments

[citrusmunch]

maybe related to #2320?

[BorisTheBrave]

It's not related to #2320.

If I've understood correctly, c1.animate.set_stroke(...) works by cloning c1 into c1.target, then calling set_stroke on the target. The animation then Tranforms from c1 to c1.target, but never actually edits c1 beyond that.

I would propose a decent fix would be to that c1.animate.set_stroke should call c1.set_stroke at the appropriate time, possibly during the finish step of the animation.