Saving built-in script as file suggest tres extension

[KoBeWi]

Godot version:
3.2 beta2

Steps to reproduce:

1. Add a node
2. Add a built-in script to it
3. Go to the script in the inspector and save it as file
   
4. This happens
   

You can either manually enter correct extension or select "All files" filter and then "gd" again.

EDIT:
After some more testing, this also happens when you save the script from the Script Editor (Ctrl + Alt + S), but only after the scene was saved with the script.

[lyuma]

Still a bug on master (4.0 alpha 11)