'The callback that will be called by LibtorrentMgr when a download failed.'

@call_on_reactor_thread
def _failure_callback(self, infohash):

    if (infohash not in self._running_requests):
        self._logger.debug(u'++    failed    INFOHASH:    %s', hexlify(infohash))
        for ih in self._running_requests:
            self._logger.debug(u'++    INFOHASH    in    running_requests:    %s', hexlify(ih))
    self._logger.debug(u'failed    to    retrieve    torrent    %s    through    magnet', hexlify(infohash))
    self._running_requests.remove(infohash)
    self._requests_failed += 1
    self._start_pending_requests()
