If you have a curved track (in screenshot below) following the exact schematics i showed you you will get the bug happening when the sticky piston pushes down the redstone block, then pushing down the rail but however this isn't supposed to happen. The sticky piston should not of pushed at all and the rail should not stay there. However this can be some great use for roller coasters and traps. If no redstone torch is under the curved rail, it will not work. If no 2 redstone torches are next to each other it will not work. Hopefully you will start looking at this and hopefully this will be removed. Thanks!

Steps:
1. Place a rail
2. Right at the left of it, dig 2 blocks down, then place a torch
3. Cover and place powered rail over
4. Add the other track right under it
5. Dig 3 blocks down on the left side of the curved rail
6. Dig 1 block right under the curved rail, you should see a redstone torch
7. Place a redstone torch
8. Seal it up
9. Add 3 blocks on top of the curved rail
10. Destroy the bottom 2
11. Add your sticky piston facing down
12. Add your redstone block right under it and right on top of the curved rail
13. Add a button on the very top block
14. Activate and watch