Fix no-args check in user search endpoint
Fix no-args check in user search endpoint

DirkHoffmann/indico,mvidalgarcia/indico,mic4ael/indico,OmeGak/indico,indico/indico,DirkHoffmann/indico,OmeGak/indico,pferreir/indico,OmeGak/indico,pferreir/indico,mic4ael/indico,mvidalgarcia/indico,mvidalgarcia/indico,indico/indico,indico/indico,indico/indico,DirkHoffmann/indico,ThiefMaster/indico,mic4ael/indico,DirkHoffmann/indico,ThiefMaster/indico,mic4ael/indico,pferreir/indico,ThiefMaster/indico,OmeGak/indico,pferreir/indico,mvidalgarcia/indico,ThiefMaster/indico