Some rail types don't drop as items when pushed with pistons over non-solid blocks

Powered, activator and detector rails don't drop as an item when pushed with a piston or sticky piston over air or any other block they shouldn't be placed on.

What I expected to happen was...:
I expected them to drop as items when pushing them over non-solid blocks.

What actually happened was...:
The rails didn't drop as items when pushed over a non-solid block.

Steps to Reproduce:
1. Place any type of piston facing a detector, activator or powered rail
2. Replace the block the rail is going to be moved on to with a non-solid block or air
3. Activate the piston