This allows rclone to exit with a non-zero return code if no files are
transferred. This is useful when calling rclone as part of a workflow/script
pipeline as it allows the end user to stop processing if no files have been
transferred.
NB: Enabling this option will return in rclone exiting non-zero if there are no
transfers. Depending on how your're currently using rclone in your scripts,
this may break existing setups!