Cactus flowers cannot be replaced when attempting to place blocks in the same space as them

The Bug:

Cactus flowers cannot be replaced when attempting to place blocks in the same space as them.

Steps to Reproduce:

1. Place down a cactus flower.
2. Attempt to replace the cactus flower with a solid block.

Observed Behavior:

Cactus flowers cannot be replaced.

Expected Behavior:

Cactus flowers would be able to be replaced.