The redstone on a piston gets dropped when the piston is activated

Put the summary of the bug you're having here

What I expected to happen was...:
The redstone/redstone repiter/lever/redstone comparator/etc must not gets dropped when the piston is activated unless it is on the moving side of the piston
What actually happened was...:
The redstone/redstone repiter/lever/redstone comparator/etc on a piston gets dropped when the piston is activated
Steps to Reproduce:
1. Place a piston horizontally
2. place a lever on the piston
3. and activate the lever