Summary:
Huge mushrooms can't be grown using bonemeal (Beta 1.2.13.5 Win 10).

Steps to reproduce:
Creative/survival
1 Create a flat world
2 Place down a block of Podzol or Mycelium
3 Place a brown or a red mushroom ontop of the Podzol or Mycelium
4 Apply bonemeal numerous times
5 Observe the mushroom to never grow into a huge mushroom

What i expected to happen:
The mushroom to grow into a huge mushroom when applying bonemeal, as it is working in 1.2.10.2.