I've found a bug during some attempt to learn about redstone, i did some research and it seems i'm the first one to find this bug.
Steps to recreate:
1.Get a piston (sticky or not), a redstone block, and any above-piston-placeable block
2. Put the block on the next positive Y axis coordinate (y+1)
3. Put the redstone block above the block
4. Take out the middle block and then the redstone block

I couldn't find any purpose of abuse of this bug yet it is still a bug so...i felt like reporting it.

As i'm not near a computer i can only put a link to a video in Spanish i made explaining this bug and a recreation of it:
https://youtu.be/n7TcJvS8m_M