Custom skins become Steve when Star Wars texture pack is active

When applying the Star Wars Mash-up Pack, all saved skins become Steve

How to reproduce

1) Create a custom skin

2) Create a world with the Star Wars texture pack (requires purchase of the Star Wars Mash-up Pack if you don't have it already)

3) Enter the world and open Dressing Room to see every slot is Steve

Expected result- no skins are replaced with Steve
Actual result- all custom saved skins become Steve