If you want to match the tune in Stanford-Petrie, you should also change 'dorian' to 'mixolydian'. All mode seems to do in ABC is change the number of sharps or flats on the key signature, (and they are played as the key signature indicates). In the tune above you could call it G mixolydian (no sharps or flats), and it would still play and display as D dorian (no sharps or flats).