In version 1.4, turrets can now be covered by adjacent objects, but 2x2 or larger turrets can only take cover on the bottom-left-most tile.
In other words, when attacked from the upper right, turrets are considered uncovered and don't receive any cover effect.
This mod allows 2x2 or larger turrets to be covered by adjacent object in all directions.
This means that the behavior is exactly the same as when this mod was used in version 1.3.