Setter called twice if script is extended in instance

[KoBeWi]

Tested versions

4.4 dev7 and earlier

System information

W10

Issue description

Given this simple script:

extends Node

@export var skin: String:
	set(s):
		print(">", s)
		skin = s

There are cases when the setter will run twice (as evident by double print). This happens when you attach the script to a node and save as scene, then instantiate the scene in another scene, set the property to a different value in the inspector and extend the script. When you run the scene, the setter will be called with the default value and then your exported value.

Steps to reproduce

Run MRP.

Minimal reproduction project (MRP)

SetterBug.zip

[AlbePie]

I'm not sure about this, but I think this is an intended behavior. Godot first loads the instanced scene without overrides, which causes the first print, and then applies the override, causing the second print. Again, this is only my hypothesis, it's possible that it is not intended.