Arrows can pass through signs/hanging signs.

When shooting an arrow at a sign/hanging sign the expected result is for the arrow to hit the sign and get bogged down, but it goes through the sign instead.

How to reproduce

Start by crafting a sign or hanging sign
Then obtain a bow and some arrows 
Place the sign and target the sign using your bow, it will pass through the sign.

Observation: The arrow passes through the sign.
Expectations: The arrow should interact with the sign just like any other block.