Withers sometimes rapidly jitter when chasing and shooting at their targets

The Bug:

Withers sometimes rapidly jitter when chasing and shooting at their targets.

Steps to Reproduce:

1. Summon a bunch of chickens and a wither.
2. Watch closely as the wither approaches and shoots at the chickens.

Observed Behavior:

Withers sometimes rapidly jitter.

Expected Behavior:

Withers would not rapidly jitter.