Horse armor does not render with any resource pack equipped

When equipping any resource pack horse armor textures do not render

reproduce
have any resource pack equipped

observed 
Invisible horse armor with resource packs

expected 

horse armor should still be visible with resource packs unless resource pack:
. Adds a horse texture
 it might be failing to fall back to the default textures when the resource pack doesn’t provide specific textures for horse armor, resulting in the armor becoming invisible. However even when providing texture files for horse armor the horse armor still does not work. I'm assuming there's something wrong with the internal structuring for horse armor resource pack file reading. (Not handling the absence of a texture properly)

 

images are from a blank resource pack with nothing but a manifest file, The horse has diamond armor.