Wither skeleton note block sound plays normal skeleton ambient sounds instead of unique ones

The wither skeleton skull on top of the note block plays normal skeleton ambient sounds instead of unique ones.

Step to Reproduce:
1. Place down two note block
2. Place down a normal skeleton skull and a wither skeleton skull on each top of the note block
3. Play the note block.
4. Pay attention to the sound differences.

Heard Result
Wither skeleton skull plays normal skeleton ambient sounds.

Expected Result
Wither skeleton skull should play its own unique ambient sounds.