Fix umount when virtiofs was never used (slice does not exist).

roles/lmn_vm/files/pam-umount.sh

@@ -30,9 +30,9 @@ if [[ "$mtp" =~ "/lmn/media/$usr/share" ]] ; then
     sleep 5 # leave some time to write caches …
     sudo -u ${usr} killall gvfsd | systemd-cat
     sudo -u ${usr} killall dbus-daemon | systemd-cat
-    systemctl kill system-virtiofs.slice
+    systemctl kill system-virtiofs.slice || true
     # debug to find processes blocking umount:
-    # lsof > /tmp/lsof.log
+    # lsof >> /var/log/lsof.log
 fi
 
 ## Just umount: