The top bars of wall hanging signs aren't culled by blocks that completely cover them

The Bug:

The top bars of wall hanging signs aren't culled by blocks that completely cover them.

Steps to Reproduce:

1. Build the setup as shown in the provided attachment. setup.png
2. Go into spectator mode and look at the sides of the top bar of the hanging wall sign that are completely covered by adjacent blocks.
3. Take note as to whether or not the top bars of wall hanging signs aren't culled by blocks that completely cover them.

Observed Behavior:

The top bars of wall hanging signs aren't culled by blocks that completely cover them.

Expected Behavior:

The top bars of wall hanging signs would be culled by blocks that completely cover them.