Fix session block migration
Fix session block migration

don't add legacy mapping in case of a block from a zombie session

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