bone meal from dispensers wont grow grass

Bone Meal shot from Dispenser will not grow grass on grass blocks.

Steps to reproduce:

1. Place dispenser on grass blocks.
2. Place stone block behind with a button on it
3. Fill dispenser full (all slots, 64 stack) of bone meal
4. Press button

If the block in front of the dispenser has seeds, melon or tree sapling, they will grow after a couple clicks of the button.

If the block in front of the dispenser is a grass block, nothing happens. It should cause grass/flowers to grow.