You couldn’t call Erykah Badu one of the world’s most productive artists: it’s 12 years since her last album, and she’s released just five of them in 25 years, plus a couple of mixtapes. You’re more likely to see her name in the papers for something stupid she’s said – that she can see the good in everybody, even Hitler, because he was ‘a wonderful painter’, for example – than because she’s done something musical.