Even before it’s debuted at the American Repertory Theater, a revival of the 1972 musical “Pippin” slated to run next winter at the ART is attracting the attention from folks on Broadway. The New York Times reported Tuesday that longtime Broadway producers Barry and Fran Weissler are “very interested” in backing Diane Paulus’s production of “Pippin.” (Paulus, of course, is the artistic director of the ART whose musical “The Gershwins’ Porgy and Bess,” just won a Tony.) While confirming the Weisslers’s interest, a spokesman told the Times that talk of a Broadway move is premature, and he declined to quantify the Weisslers’ financial support.