The Bug:

Withers' shoulder heads always spawn facing south despite a rotation value being provided.

Steps to Reproduce:

1. Summon a wither that's facing north by using the command provided below.

   /summon minecraft:wither ~ ~ ~ {NoAI:1b,Silent:1b,Rotation:[180f,0f]}

2. Watch the wither's shoulder heads closely.

Observed Behavior:

Withers' shoulder heads always spawn facing south and then gradually rotate to the correct position.

Expected Behavior:

Withers' shoulder heads would spawn facing the said direction upon being summoned.