It seemed pretty fortuitous for Donald Trump. He left heads scratching when he told a crowd of supporters at a rally in Florida on Feb. 18: "You look at what’s happening in Germany, you look at what's happening last night in Sweden. Sweden! Who would believe this? They took in large numbers [of refugees]. They’re having problems like they never thought possible." A nice play to anti-immigrant hysteria, but there was one hitch: nothing had happened in Sweden the previous night. Critics had a field day with the bizarre flub, with Swedish activists even holding a mock "Pray for Sweden" vigil to taunt Trump. So it seemed a godsend for the prez when an immigrant district of Stockholm exploded into riots just three days later.