This is a story about corporate and investor strategy, government meddling, and chocolate. (Cue Homer Simpson…) It involves the Hershey Company, the pioneering U.S. chocolate maker. Typically, Hershey is the top seller of candy in the United States—but it is not the largest U.S. candy maker. That distinction goes to its bitter rival, Mars Inc., which has larger global sales. (For a history of the rivalry, including tales of corporate espionage, see Joël Glenn Brenner’s The Emperors of Chocolate.) Hershey...