There's a familiarity to the tune; it could almost have been modelled on Yarmouth Town (at least as Peter Bellamy sang that song). Whether the respective dates fit (Dylan certainly picked up a number of tunes while playing in the UK, and re-cycled them almost immediately) I wouldn't know. Bellamy reckoned he'd "collected" Yarmouth Town from an (unnamed) Norfolk singer, but the tune does sound rather like an American "old time" piece; more so than Dylan's tune, to my ear.