The first time Jann Wenner put John Lennon and Yoko Ono on the cover of Rolling Stone, in 1968, he was propping up his fledgling publication. The second time, in 1981, he was sealing Lennon’s legend. With the magazine now up for sale, Joe Hagan chronicles the relationship between Wenner and Lennon in an adaptation from his new biography of the Rolling Stone founder.