When a mine cart passes over the detector rail it raises up a piston. The piston is supposed to go down after the cart passes. What happens instead is the redstone under the detector rail stays lit until you destroy the detector rail and the block it was sitting on.
Environment
Windows 7, Java 64 bit version 7 update 10
Duplicate of MC-5788 , please use the search function to see if your bug has already been submitted. Currently over 40% of tickets are being closed as duplicate.