Save warning doesn't show when you save a built-in resource as an external resource

[stephannv]

Tested versions

• Reproducible in: 4.3.stable

System information

Godot v4.3.stable - macOS 14.2.1 - Vulkan (Mobile) - integrated Apple M1 Max - Apple M1 Max (10 Threads)

Issue description

When you close a scene after saving a built-in resource as an external resource, you don't get a warning to save your scene and you lose your modifications.

pb21.mp4

I expected a confirmation dialog like this after saving external resource and closing scene:

Steps to reproduce

• Open a scene containing a built-in resource
• Save the resource as an external resource
• Close the scene
• You don't get a warning to save your scene
• Your scene keeps using a built-in resource instead the external resource

Minimal reproduction project (MRP)

N/A

[Hilderin]

I was able to reproduce 4.3.stable and 4,4 dev master.