Although Hal Ashby directed a remarkable string of acclaimed, widely admired classics throughout the 1970s — “Harold and Maude,” “The Last Detail,” “Shampoo,” “Coming Home,” “Being There” — he’s often overlooked amid the crowd of luminaries from his generation. Amy Scott’s exuberant portrait — drawn from rare archival materials, interviews, personal letters, and audio recordings — explores that curious oversight, revealing a passionate, obsessive artist. Having hitchhiked to LA, Ashby eventually landed in the editing room, where a chance encounter with Norman Jewison brought his big break (and a lifelong friendship). Ashby’s subsequent films were guided by compassion and deep engagement with social justice, class, and race. “Hal” plays on a double bill with a restored version of “Shampoo,” one of the director’s finest works.