Chicago footwork producer Morris Harper, better known as DJ Spinn, had the best set at this summer’s Pitchfork festival. His early-evening slot on the fest’s last day overlapped with performances by reunited British shoegaze band Slowdive and electro-pop darling Grimes, but his turnout didn’t seem to suffer for it. The tree-shaded Blue Stage felt like a family reunion; dozens of friends and colla