The man on stage would like you to call him Yasiin Bey. “Ali, not Clay,” he says. That doesn’t stop the gig’s posters and tickets from bearing the name Mos Def in larger lettering than that of his name of choice, however. Coming on stage around 10pm in an oversized scarf and baggy tee, he opens with ‘Cream of the Planet’, an unreleased track from 2010. Though billed as a fifteenth anniversary celebration of 1999’s breakthrough release Black On Both Sides, the night sees Bey jump from era to era, appropriately enough as 1982’s seminal hip-hop flick Wild Style plays…