Oxford dictionary of English Etymology (1966 edition):

Jubilation. exultant, rejoicing. 14 C ( Wycliffe Bible). - Latin jubilatio(n-), f.jubilare.
(Rustic word) Call, halloo.
rest of entry irrelevent.

It's an old, rustic word, synonomus with halloo, a cry from hunting.
Given a few centuries of the folk process to fudge it, I'd take that as an origin.

Bunnahabhain