'rsync -del' and 'rsync --del' are two different commands.  We cannot let '-del' imply '--del'

See:
 rsync -h | egrep '( -[del]|del )'
  -d, --dirs                  transfer directories without recursing
  -l, --links                 copy symlinks as symlinks
  -e, --rsh=COMMAND           specify the remote shell to use
      --del                   an alias for --delete-during