The legs of a sheep and its wool cannot be independently retextured

The first trackable version this issue affected is Minecraft 1.4.2*
The four legs of a sheep and its outer wool cannot be independently retextured from one another, making them always look the same. This is limiting to the player's resource pack creativity and freedom to edit the texture.

Steps to Reproduce:

1. Download and apply the following resource pack:

1. Spawn/Summon a sheep

Observed Behavior:

All four legs of the sheep will look entirely red (with the outer wool layer being blue), despite the player seemingly only modifying one leg in the UV map.

Expected Result:

Only one of the legs would be altered, since that is what the player intended to change. The current behavior is unexpected and not resource pack friendly.

Screenshots/Videos: