3D Mushrooms are rendered very strangely when on Mooshrooms, It looks like the wrong faces are being culled, but i didn't set any faces to be culled on the red mushroom model.

I suspect this reveals some obscure issue with the block model rendering code.

Direct download to my texture pack, if you want to see the scripting:
http://www.jwbjerk.com/lithos/Lithos%20Core.zip

EDIT:
Sorry this is a duplicate. I did search first but missed:
https://bugs.mojang.com/browse/MC-50769