This iStage Performance Ensemble production of “Pippin” draws inspiration from the Bob Fosse film “All That Jazz,” turning the Mephistophelean Leading Player into a dual role— a brash circus master (Ben Vereen’s O’Connor Flood) and the seductive, comforting embrace of death (Jessica Lange’s Angelique). The traveling troupe of players “find” their show materials from the grounds of the space itself, incorporating props and costumes from previous (and concurrent) main stage productions, including “Frog and Toad” and “The Hula Hoop Queen.”