sky-texture bug

Just after downloading the latest snapshot, I went to my test-world on single player to fiddle with the new stuff, and soon the sun began to set and when I looked at the sky I saw what's i nthat picture, wierd green patches that flashed on and off quickly. It took me a few tried to get a photo because it was so fast. It only appeared when I looked a tthe sky at a certain angle, it I moved my view over to any side it would disapear.