John Prine's Hobo Song

I was at a circle jam yesterday, and the gal next to me called a tune in the circle jam that I didn't know by name, but the first 8 bars were almost exactly John Prine's Hobo Song.  Because I'd played it quite a bit as Hobo Song I quickly fell into it, then she called me to take it.  I wonder if I can find out anything at Fiddle Hangout about whether Prine consciously borrowed this melody.