Editing a sprite key during playback stops eval (scene no longer updates), even if playback continues to loop... see attached gif

repo:
-import attached package
-create an anim clip with one of the two sprite sequences
-hit play in the AW
-while the animation is playing, edit a sprite key by moving it over time...
bug: scene stops evaluating, but play keeps looping.
expected result: key edit does not stop eval, exactly like in 5.4, and animation keeps playing.

repro in 5.5.2f1, 5.6.0b9, 2017.1.0a1
regression since 5.4, not repro in 5.4.3f1