Tall Flower/Grass Bug

Double tall flowers/grass change the upper block into an other flower after destroying the bottom block of the tall flowers/grass.

What I expected to happen was...:
Destroying the flower/grass without changing the block.

What actually happened was...:
It changed.

Steps to Reproduce:
1. Place tall grass/flowers
2. Break bottom block of the grass/flowers

Sometimes it does not work but sometimes it does. be sure that you don't test it on the flower where it changes to.