The bug

When either a powered rail, activator rail or a detector rail is pushed onto farmland using a piston, it does not drop the rail or get pushed onto the farmland. This does not happen for regular rails, those drop when being pushed onto farmland.

To reproduce

1. Get either a sticky piston or a regular piston and place it down
2. Put a powered rail, activator rail or detector rail to be pushed by the piston
3. Place farmland so that the piston will push the rail onto the farmland
4. Activate the piston