code: def add_url (self, url, line=0, column=0, page=0, name=u"", base=None):
          
          webroot = self.aggregate.config["localwebroot"]
          if webroot and url and url.startswith(u"/"):
              url = webroot + url[1:]
              log.debug(LOG_CHECK, "Applied local webroot `%s' to `%s'.", webroot, url)
          super(FileUrl, self).add_url(url, line=line, column=column, page=page, name=name, base=base)
docs: If a local webroot directory is configured, replace absolute URLs
          with it. After that queue the URL data for checking.