I'm not entirely sure this is a bug, but you can place blocks where you are standing and it pushes you out of the way when doing so.

What I expected to happen was...:
I expected it to not let me place a block where I was standing.

What actually happened was...:
I was able to place a block where I am standing, and it would push me out so that I wouldn't be inside the block.

Steps to Reproduce:
1. Place a block where you are standing, I used Oak Wood Logs.