This cut from sessions for the National’s Trouble Will Find Me floated around last year, and now it’s official: “Learning,” the title track on Perfume Genius’ debut, is the new B-side to “I Need My Girl.” Substitute the emotive tenor of Mike Hadreas for Matt Berninger’s road-weary baritone and you have a faithful take, reverent to the original while well at home among the National’s own brand of defeated repose.