A Wither's shield glows red from damage instead of the Wither itself

The shield Withers gain when they reach half health will glow red when damage is taken instead of the Wither's body glowing red.

Steps to Reproduce:
1. Make a new Creative world.
2. Spawn a Wither.
3. Enchant a diamond sword with Smite V and bring the Wither down to half health.
4. When at half health, attack the Wither with your fist and notice its arrow shield glows red.