stock, stock.move, onchange_lot_id

def onchange_lot_id(self, cr, uid, context=None, prodlot_id=False,
product_qty=False, loc_id=False, context=None):

replaced by:

def onchange_lot_id(self, cr, uid, ids, prodlot_id=False, product_qty=False,
loc_id=False, context=None):

It was a bug introduced recently (not present in previous versions, I
think), the call in the view was correct.

--
Fabien