MinecraftForge/MinecraftForge — pull request #995 by iChun (2014-03-10 22:31:12+00:00)
Title: Fixes stencil bits not existing in Minecraft's framebuffer causing stencil test to not work.

Basically checking if there are reserved stencil bits in the Display (which Forge already checks for) then using the correct OpenGL constant to supply the correct render buffer.