When you are very close to a piston, it run through you. Sometimes happens, sometimes not.

Put the summary of the bug you're having here

What I expected to happen was...:
That piston pushed me.
What actually happened was...:
The pìston run through me.

Steps to Reproduce:
1. Put a piston, horizontally.
2. Move closer to the piston.
3. Turn it on.
If it doesn't happen, try again.