the armour sleeves on spider jockeys will move but the skeletons arms stay still.

The armour sleeves on spider jockeys move while the skeletons arms stay still.

What I expected to happen was:
the arms of the armour to stay with the movement of the skeletons arms (if any).

What actually happened was:
the armour sleeves on spider jockey were moving while the skeletons arms stayed still.

steps to reproduce:
1. Find a spider jockey with armour
2. look at its armour sleeves