Rail Duplication Bug

Standard rails can be duplicated when the are moved by a sticky piston (does not affect other rail types).

This happens when the rails are pulled from a solid block into the air, then pushed back onto the block.

The rail should break as soon as it is moved off a block.

Steps to Reproduce:

• Using a sticky piston, pull a rail from a solid block, and then back again
• The rail moves, but a second rail is dropped
• This can be repeated, duplicating the rails infinitely.