(This issue first appeared in Minecraft 1.4.2 when the wither was added)
All three ribcages (top, middle, and bottom) and the right/left heads of the wither boss cannot be independently retextured from one another, making them always look the same, limiting the player's resource pack creativity.
This affects both the base texture (wither.png) and the invulnerable texture (wither_invulnerable.png).

Steps to Reproduce:

1. Download and apply the following resource pack:
   Wither.zip
2. Spawn, or create a wither boss using blocks

Observed Behavior:

The three ribcages and 2 side heads will look entirely red, despite the player seemingly only modifying one ribcage and one head in the UV map.

Expected Result:

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

Screenshots/Videos:

Notes:

Related independent retexture issues:
MC-271355 MC-271384 MC-271383 MC-271368 MC-271363 MC-271357 MC-271355 MC-271354 MC-271330 MC-271305 MC-271304 MC-271232 MC-264571 MC-270516 MC-270517 MC-145334 MC-265343 MC-265345 MC-270530 MC-271767 MC-271768 MC-271769 MC-271770 MC-271773 MC-271780 MC-271982 MC-271988 MC-271989
Related wither model issues:
MC-194120 MC-181389