No large red mushrooms in mushroom biomes 1.8.2 onwards

Also saw this with red mushrooms. Only big red mushrooms in the whole biome.

It appears that in 1.8.2 they changed the "generate big mushroom" class from storing 0 for brown or 1 for red or -1 for choose randomly to storing the blockstate for brown/red and null for choose randomly.

But at the same time they changed the choosing randomly from storing in a local variable to updating the field on the "generate big mushroom" instance, which has the effect that it chooses randomly exactly once for all the mushrooms in all the mushroom islands in that play-session.

I created a Mushroom Island world (1.8.3) and I got many large red mushrooms and very few large brown ones.
My observation: they seem to form some kinda sub-biomes within the MushroomIsland biome: areas with brown mushrooms, areas with red ones, and areas with both.

Still present in 15w32b