The displayed icon for the grass block is incorrect (I have put the programmer pack between default and golden days)

I'm pretty sure this is intentional, due to the fact that the pack is centered around alpha/beta style textures

Yep! This is intentional as in beta 1.7.3 that is how the grass block appeared due to it being unobtainable in survival. If you don't like it, just delete the grass_block.json in assets/minecraft/models/item/