There is a startlingly similar tune from Sephardic tradition - on the Voice of the Turtle recording "Balkan Voices, Spanish Dreams", it's "Ken es akeyo de la meniana", whose source is given as Avraam Altarats of Sarajevo. Judith Wachs' note says it's of Yugoslav origin, which in this context presumably means Bosniak. It ends a tone higher than Wayfaring Stranger, though it doesn't really sound Phrygian.