[Affecting Live] Armor is visible on mobs that it shouldn't be.

Verification builds: 1.7.0.2 - R7 Beta 21 Build 1117901

Summary:

If you put armor on mobs that don't fit the current armor model, the armor displays on them anyway. Pigs, spiders, chickens etc look silly with humanoid armor pieces hanging off them.

Impact:

This is a graphical issue which makes the look of the mobs stupid. I use helmets in Mutant and Monster Battle Arena to set their teams and behaviors, the result is both hilariously bad and unpolished.

Repro Steps:

1. Open a vanilla world
2. Turn on cheats
3. do /replaceitem entity @e slot.armor.head 0 golden_helmet

Observed Results:

ANy mobs that you see that the command worked on, will have a helmet, even though it shouldn't. The helmet is likely floating high above their heads, the same weirdness happens with any armor piece.

Expected Results:

The armor should not be visible for the mobs where the armor model doesn't fit the mob.

Screenshots/Videos attached: Yes 

Regression Build: 1.6.0.8