Empty Carpet texture pixels no longer Transparent (also true for all blocks)

Carpet no longer renders 'empty' pixels as transparent as was the case in previous versions.

(I know this is a very selective bug, as it takes its texture from wool blocks and thus wouldn't need the transparency in a normal setting, but I actually use carpet with transparency alot in my custom texture packs for very spercific builds )

This effect is also true on all blocks not usually using transparent pixels (probably intended and not a bug), but extends to 'non-solid' blocks using same textures (stairs / halfslabs / carpets / etc )