DePaul University freshman David Krupa scored an impressive victory in Chicago politics on Saturday: Boss Madigan — the most powerful Democrat in Illinois — backed out of a challenge to Krupa’s candidacy for alderman in the Southwest Side’s 13th Ward. “I am truly humbled to be the first candidate on the ballot to challenge the 13th Ward since 1991,” Krupa, 19, told me at the Chicago Board of Election Commissioners offices. A few political guys mumbled privately that Madigan must be so angry that he might as well fill a burlap bag of the severed heads of a few of...