Yes, you can't remove it here. I know it is lame but the way this is coded works. If you look at neutron::server class you see this:

  if $sql_connection {
    warning('sql_connection deprecated for connection')
    $connection_real = $sql_connection
  } else {
    $connection_real = $connection
  }

This looks fine but sql_connection is always set, so connection_real will always be set to sql_connection. So for now just set them both. Or perhaps we can set sql_connection to undef?