This year’s 71st Venice Biennale international film festival showcases one of Italy’s more polemical new films: actor Sabina Guzzanti’s 100-minute “The Barter, Investigation into a the State-Mafia Negotiation.” The story is based upon a deal believed to have been worked in the earlier Nineties which allegedly resulted in a peace treaty between the Italian authorities and the Sicilian Cosa Nostra under Salvatore (“Toto’”) Riina. The film comes at the same time that the trial – the real trial – over this alleged affair is taking place in the real Palermo.