Minecraft snow layer and bed lighting bug (and probably for more half blocks)

Lighting is bugged on snow layer blocks when using any smooth lighting minimum or maximum, and same for beds when placed near glowstone block, also check other half blocks too, carpets, slabs, etc, placing them near glowstone blocks or other blocks.

http://i.imgur.com/Q4j99DB.png
http://i.imgur.com/gxQgQJf.png

What I expected to happen was...:
no shadow in these block should appear

What actually happened was...:
shadow appeared.

Steps to Reproduce:
1. Put a bed near glowstone, or snow layer above grass block.
2. Turn smooth lighting on minimum or maximum.
3. Lighting is bugged.