Block crack is offset for skulls if they're placed against a block

Place a skull against a block and start breaking it. You'll notice that the block crack doesn't quite resemble the skull itself as cracking, but rather, the block outline itself where the skull is completely ignored.

Notice after MC-183915 was fixed:
Now, in some cases, multiple crack layers appear once the skull starts cracking.

Additionally, the cracking layers can shift on the skull while the animation is playing.