The political race has given fuel to two must-see Sunday night shows on premium cable. The one that arrives first is Showtime’s The Circus, which affords backstage and on-the-scene looks from the campaign trail. And the reason it’s must-see is because of what’s been happening, week in and week out, on that trail. Happy trails to you? Not on this show… but divisive, disappointing, surprising, even violent? The gang’s all here.