I can't answer your actual question. I don't have time to look into looking into that changeset.
But you could probably try the following to manually change the external editor:
1. Find your octaverc-file: <Octave-Install-Dir>\share\octave\site\m\startup\octaverc (in Windows, should be the same in Linux except for slash direction or may be in Linux, you'll have <Octave-Install-Dir>\.octaverc).
2. Add the following line: "EDITOR('<Editor's Full Pathname>');", for example "EDITOR('C:/Program Files (x86)/Notepad++/notepad++.exe');