Dead bushes cannot be placed on farmland

The Bug

This is very inconsistent behaviour with all other plant blocks, which can be planted on both grass and dirt and its variants.

Steps to Reproduce

1. Build the setup as shown in the attachment below. setup.png
2. Obtain some dead bushes and attempt to place one on each of the six blocks.
3. Take note as to what blocks you can place dead bushes on and what blocks you can't.

Observed Behavior

Dead bushes cannot be placed on farmland.

Expected Behavior

Dead bushes would be able to be placed on farmland.