Skip startup script setup on 18.04 (refs #25525).

5.MediaServer/2.Startup_check_script_for_NFS/0_setup.py

 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
+import os
 import utils
 
 
 def setup(interactive=True):
     dir_path = utils.get_dir(__file__)
     # This script should be installed only if the home partition is a mount point
+    if not os.path.isfile('/etc/rc.local'):
+        utils.log('The /etc/rc.local file does not exists, action skipped. See ticket "https://redmine.ubicast.net/issues/25525".')
+        return
     cmds = [
         dict(line='write', template='%s/check_services.py' % dir_path, target='/usr/local/bin/check_services.py'),
         'chmod 755 /usr/local/bin/check_services.py',