Viewport's "Handle Input Locally" inside ViewportContainer gets set to false after scene reload

[kuhnchris]

Godot version:
Godot Engine v3.2.4.rc.custom_build.ba174332a - https://godotengine.org

OS/device including version:
Linux (Arch), AMD, GLES3 (not relevant)

Issue description:
The flag on "handle_input_locally" on a Viewport within a ViewportContainer keeps getting reset to false whenever the scene is getting reloaded, despite "true" being the default option.

Steps to reproduce:

1. Create new project
2. Create new scene
3. Create ViewportContainer
4. Create Viewport within ViewportContainer
5. Set size so Godot is satisfied
6. Save Scene
7. Close Scene
8. Open Scene again
9. Check Viewport's handle_input_locally property

Minimal reproduction project:
MinimalDemoViewportIssue.zip

[kuhnchris]

Could this be the potential issue?

godot/scene/gui/viewport_container.cpp

Line 125 in 1d0929a

c->set_handle_input_locally(false); //do not handle input locally here

If yes, is there any reasoning for this?
Maybe I'm just not understanding ViewportContainers properly.

Thanks!

[Calinou]

Closing in favor of #56502, which is more detailed.