inheritance and collision shape

[bloodre]

Here is an example:
The pickable_item scene has a given collision shape fitting a crate. Heal_item should have a smaller collision shape to cover the carrots. I changed this collision shape in heal_item.tscn to fit the carrot.

Once the game runs, by shooting at the heal_item, I can observe the hitbox is still the crate's one.

The only fix I found was removing the inheritance which isn't practical.. I found this:
godotengine/godot#8103
But it either doesn't do the trick or I failed to apply it correctly.