Hanging signs connected to the side of the block don't break if the connected block is broken.

Hanging signs connected to the side of the block don't break if the connected block is broken.

What I expected to happen was...:
I expected the hanging sign to break.

What actually happened was...:
The hanging sign stayed/

Steps to Reproduce:
1. Place any block.
2. Place a hanging sign of any variation on the side of the block (not the bottom).
3. Break the block that is supporting the sign.