function allowDoubleForwardSlash(req, res, next) {
  req.url = req.url.startsWith('//') ? req.url.substring(1) : req.url;
  next();
}
Express 4 allowed a double forward slash between a route and router. Although
this should be considered an anti-pattern, we need to support it for backwards
compatibility.

Technically valid URL with double foroward slash:
http://localhost:1337/parse//functions/testFunction