Supreme Court Justice Ruth Bader Ginsburg is a bona fide pop icon, perhaps strange territory for an 85-year-old, diminutive, reserved constitutional scholar. In the latest Political Theater podcast, filmmakers Betsy West and Julie Cohen speak about their documentary, “RBG,” including what it was like to be in the same theater when Ginsburg saw their movie at the Sundance Film Festival. The documentary opens in theaters on May 4.