Moscow last Saturday celebrated its annual city day and 875th birthday. As spectacular fireworks erupted over Red Square, Sergey Shnurov took to the stage across town at Luzhniki stadium as frontman for the ska-punk band Leningrad.  A raucous group known for their provocative and often foul-mouthed songs and music videos, Leningrad have a huge following across different generations and a cross-section of Russian society.  Like President Vladimir Putin, Shnurov is from St. Petersburg, which was known as Leningrad until the Soviet Union collapsed. He is regarded as a deranged court jester or a yurodivy – a holy fool whose insanity gives…