Miley Cyrus revived her Backyard Sessions series for a new MTV Unplugged performance this weekend. She and her masked band, dubbed "the Social Distancers," played a whole bunch of covers: Pearl Jam’s "Just Breathe," the Cardigans’ "Communication," Britney Spears’ "Gimme More," Nico’s "These Days," and the Velvet Underground’s "Sweet Jane." Only pieces of her set…