There were some people who looked at the draw for the 114th edition of the French Open more than a fortnight ago and imagined there was at least a reasonable chance the Swiss national anthem would be played on the final Sunday. But none of them, surely, thought the man gently humming it to himself would be Stan Wawrinka, wearing what looked suspiciously like pyjama shorts, in front of a delirious crowd on a sun-bathed Court Philippe Chatrier.