The 72-year-old former general elected as Nigeria ’s new president this week is not exactly new to the democratic process: He spent much of the past decade campaigning for the office in three successive elections — and failing each time. But then, as detractors insist and many supporters acknowledge, the former general, Muhammadu Buhari, had a long way to go to prove that he had left the military barracks behind. He first came to power in a coup over 30 years ago and became one of his country’s harshest military rulers, waging a “war against indiscipline” that prescribed humiliating punishment for tardy civil servants. He publicly executed young drug dealers on the beach, jailed journalists and expelled thousands of immigrants. He arrested 475 politicians and businessmen on corruption […]