In recognizing there's only so much one can do w/3 chords and a limited scale, tunes are bound to be similar if not identical. Steve was playing alot of Celtic music at the time and I'm sure subconciously 'stole' a trad tune. As a songwriter I can speak to that particular. Have had to make subtle changes to melodies more than once. :-) Lyrics, too!

Afa the tune goes it DOES sound familiar...I've always thought that, but I just figured it to be a case of 'subconcious borrowing'. If one listens to a copy of the Del McCroury Band/Steve Earle project from the late 90s there are a couple of instrumentals on there that sound very Appalachion/Celtic.