cubicweb-vtimeline #3292466 cannot append 'callback=onJSONP_Data' to URL already containing '?' [validation pending]

In file timeline.dev.js, this line appends "&callback=onJSONP_Data" even though "raw_data" may already contain '?':

VMM.getJSON(raw_data + "&callback=onJSONP_Data", VMM.Timeline.DataObj.parseJSON);