Shovel with the efficiency enchant doesn't work on dirt.

What I expected to happen was...:
Instant mine with efficiency 4 diamond shovel (with unbreaking and silktouch as well).

What actually happened was...:
Normal digging speed, in dirt and grass.

Steps to Reproduce:
1. Take a shovel with efficiency 4, unbreaking 3 and silktouch.
2. try to break dirt and grass.