Shears Durability Bug

What I expected: Shears would lose durability when harvesting grass, even tall grass.

What happened: Shears would not lose durability when breaking tall grass, but they would when breaking regular grass.

Reproduce:
1. Be in MC Version 1.7.10,
2. Get shears
3. Press F3 + H to open advanced tooltips
4. Use shears to break tall grass
Durability will not go down-Possible Bug