empty tags raise InvalidTag now, remove obsolete parts from test_ddfs
empty tags raise InvalidTag now, remove obsolete parts from test_ddfs

pavlobaron/disco_playground,scrapinghub/disco,beni55/disco,mozilla/disco,ktkt2009/disco,oldmantaiter/disco,seabirdzh/disco,ktkt2009/disco,mozilla/disco,ErikDubbelboer/disco,scrapinghub/disco,ErikDubbelboer/disco,pooya/disco,simudream/disco,ErikDubbelboer/disco,mwilliams3/disco,pooya/disco,mwilliams3/disco,ErikDubbelboer/disco,mwilliams3/disco,pooya/disco,beni55/disco,ktkt2009/disco,ErikDubbelboer/disco,oldmantaiter/disco,oldmantaiter/disco,seabirdzh/disco,simudream/disco,scrapinghub/disco,beni55/disco,pombredanne/disco,pavlobaron/disco_playground,discoproject/disco,ktkt2009/disco,pavlobaron/disco_playground,seabirdzh/disco,oldmantaiter/disco,pavlobaron/disco_playground,seabirdzh/disco,beni55/disco,pombredanne/disco,ktkt2009/disco,discoproject/disco,simudream/disco,seabirdzh/disco,discoproject/disco,simudream/disco,pombredanne/disco,pombredanne/disco,pombredanne/disco,scrapinghub/disco,mozilla/disco,discoproject/disco,mwilliams3/disco,pooya/disco,beni55/disco,discoproject/disco,oldmantaiter/disco,mozilla/disco,simudream/disco,mwilliams3/disco