Early on in the movie adaptation of Uzodinma Iweala’s 2005 novel, Beasts of No Nation, Agu, the preteen protagonist, and his unnamed older brother have just pulled off an impish scam — demanding money from a passing driver to remove a tree branch they themselves had hacked down to block the road — when they are accosted by a wild-haired old lady. Agu’s father, a local schoolteacher, has set aside some of his family’s land to shelter refugees displaced by the escalating civil war in this unnamed West African country — land the furious “witch woman”…