In Carly Rae Jepsen’s rich trove of gemlike pop songs, one 2019 track, “Julien,” gleams with special purity. Over a cool disco beat, Jepsen makes a promise: “To the last breath that I breathe / I’ll be whispering, ‘Julien.’” On her recent concert tour, on stages decorated with puffy clouds and silver stars, Jepsen has updated her take on Julien, a real man she once dated. He is, she has shouted at a few shows, “a dick!”