TOKYO—There are some things track fans are used to: Nobody stops the Jamaican women at these Olympics and the tireless Sifan Hassan is a contender for a medal in every distance race she enters. Other things might take some getting used to: Italy is a sprint power. It now owns the gold medal in the men’s 4×100-meter relay to go with the shocking 100-meter gold that Marcell Jacobs won. The Italian relay team made Jacobs a double Olympic champion Friday, as the country pulled off a stunner to equal Jacobs’ solo triumph five nights earlier. Jacobs ran the second leg of Italy’s 37.5-second trip around the track, and Filippo Tortu outraced Britain’s Nethaneel Mitchell-Blake to the line. Tortu, who was slightly behind at the changeover, dipped first for a .01-second victory. “We are four Ferraris,” Tortu said. The triumph set off a second bout of Italian sprint celebrations on the …