instantiate packed scene with editable children and editor connected signal cause error "signal already connected"

[rt9391]

Godot version

4.2.rc2

System information

win11

Issue description

instantiate packed scene with editable children and editor connected signal cause error "signal already connected"

Steps to reproduce

1. make a scene with a signal connection via editor(from child to parent).
2. make another scene, add the previous scene as a child, and turn on "editable children".
3. make yet another scene, then add the new scene in step 2 as a child
4. in the third scene, use PackedScene.pack() to pack the child
5. instantiate the packed scene
6. observe the error "Signal '****' is already connected to given callable"

Minimal reproduction project

BugSignalBug.zip

[akien-mga]

I can reproduce the error in 4.2-rc2 and 4.1.3-stable.

[Rindbee]

Seems related to #42161.

A duplicate of #48064.

Currently, editable children cannot edit connections in sub-scenes.

godot/scene/resources/packed_scene.cpp

Lines 855 to 857 in d76c1d0

	if (p_node != p_owner && p_node->get_owner() && p_node->get_owner() != p_owner && !p_owner->is_editable_instance(p_node->get_owner())) {
	return OK;
	}

So the connections in the sub-scene should not be parsed here.

[Rindbee]

This may be mainly due to the fact that get_scene_instance_state()/get_scene_inherited_state() will return invalid SceneState if not called in the editor.

[cixil]

This may have been fixed by #97303