When I was building a water fountain which starts below my building's roof and goes several stories down, I miscalculated the blocks where the fountain would start. As I blocked the water source, water started lowering, but in the proccess of doing so, random shadow visual artifacts started to show up around the walls and roof, while it was night.

Steps to reproduce:
Updated 1. Make sure you are playing on creative, either on the day or night
2. In a fully closed room/building, place water below the roof
3. Procceed to eliminate/block the water source block and check
4. Check for any visual artifacts

*Screenshots:
http://imageshack.us/a/img46/6038/8h58.png
http://imageshack.us/a/img13/197/kwta.png
http://imageshack.us/a/img33/1108/9wd7.png
http://imageshack.us/a/img196/7747/eo93.png
http://imageshack.us/a/img850/6059/krrf.png
http://imageshack.us/a/img29/9043/6tow.png