Paul McCartney’s played a few shows with the surviving members of Nirvana over the years, and Sunday night in Seattle, he got back into it: To mark his tour stop in Seattle, Macca brought out Krist Novoselic to hold down the bottom end of “Helter Skelter.†You may be thinking, isn’t bringing out a geographically appropriate guest exactly what Taylor Swift did on her last tour? And our answer is yes, it is exactly the same thing. We look forward to his tour stop in Princeton, New Jersey, where Sir Paul will welcome to the stage John Popper, who will play harmonica on “Love Me Do.â€