Jelly Roll was set to go on tour with Post Malone before the shows were cancelled. Amy Harris/Invision/AP When  Post Malone  canceled the first few weeks of his Live Nation stadium tour with  Jelly Roll  on Friday, the rapper-turned-country star publicly said it’s because he wants to work on new music before hitting the road. Some music sites instead cited low ticket sales, and music sources say Malone has come down with a condition that’s going around the industry right now: “Blue Dot Fever.” “Seems that Post Malone came down with a serious case of Blue Dot Fever,” said a source, “and it’s contagious.” The “blue dots” refer to available seats at a show according to a Ticketmaster seating chart. “Seems that Post Malone came down with a serious case of Blue Dot Fever,” said a source.…