[Blocking] WitherSkeleton models use their parents model

Build Version: 577908
Summary:
In the build 577908 WitherSkeleton models are appearing like their default parent models. The wither skeleton is now using the model of the normal skeleton but still uses the wither skeleton texture. This has happened to only the wither skeleton and not the stray or other models; which use parent models by default.
This has happened between build versions with no change in json. The model is not broken in 566145, but using the same template in 577908 has broken the Wither Skeleton

Impact:
This breaks one of our maps we have submitted. The Wither skeleton now only uses the model of the parent. We have no way around this issue.

Repro Steps:
1. Load template
2. Activate cheats
3. Start game
4. /setblock 1502 195 12 redstone_block
5. /tp 138 99 80 -45 0
6. /summon wither_skeleton

Talk with @avondale in the mco_noxcrew chat on slack for more information

Observed results:
The wither skeleton uses the model of the skeleton. The json does reference any other models as a parent. When using 577908 the normal skeleton model s used instead of the wither skeleton

Expected results:
When the skeleton model is not referenced in the json as a base for the wither skeleton model, the wither skeleton's model should used.

Screenshots/videos attached:

• See MCO_Noxcrew slack for files