Snow layers don't drop themselves when mined with a silk touch enchanted shovel

I am unable to collect snow layers using a silk touch shovel. It drops a single snowball as if it was broken without silk touch.

Steps to Reproduce:

1. Obtain a shovel of any type
2. Enchant the shovel with Silk Touch
3. Break a snow layer of any height with the shovel

Observed Results:
A snowball will drop from the broken snow layers.

Expected Results:
The snow layers should be dropped.