Illusioners are delusional

When an Illusioner gets attacked, it retaliates like most mobs. However, unlike most mobs, they don't stop retaliating when their target dies, meaning they shoot arrows forever, which is kind of weird, but also really funny.
Note: Some Illusioners do not suffer from this illness.
Note: It seems that they only show this strange behavior if called for help by another Illusioner.