Actual download call. Calls the underlying file downloader,
        catches all exceptions and returns the result.

def _download_wrapper(self, url, *args, **kwargs):
        """
        Actual download call. Calls the underlying file downloader,
        catches all exceptions and returns the result.
        """
        try:
            return url, self._file_downloader.download(url, *args, **kwargs)
        except Exception as e:
            logging.error("AbstractDownloader: %s", traceback.format_exc())
            return url, e