970gtx, i7, win 10
Broken version: Blender 2.79 31f2a67
Worked version : Blender 2.79b f4dc9f9d68b
Here I'm not sure if this is a bug or a change made on purpose, but I consider that because the final render is different and we are still on the same version I will consider as a bug.
As you can see from my renders the shading is a bit different.
I also attached the material on the file to test it by yourself.
The differences are very slightly so you need to slide the photos one after another.
You will see that one is brighter than another, the old version is not so bright.