Curved rails are rendered wrong from bottom

Put the summary of the bug you're having here

What I expected to happen was...:
Looking on a cow riding minecart from below.

What actually happened was...:
I land and looked at the rails from bottom. The curved ones was rendered wrong!

Steps to Reproduce:
1. Place a curved rail on a transparent block like glass or barrier and look from bottom at it. (Sorry for my bad English)