Lighting Glitch on Partial Blocks

Warning - Copy of MC-123117

All partial blocks, such as Stairs, Slabs, and Path blocks, have the "missing" part of the block colored black, as if there was no light effecting it.

Relevant Settings:
Graphics - Fast
Smooth Lighting - Off

To Replicate:
1. Place Stair Block of any kind.
2. View black spot in missing quarter of block.

I was unable to post the picture on a comment for MC-123117, so created a new issue.