Don't back up backup files.

files/scripts/backup_system.sh

@@ -38,7 +38,8 @@ sudo rm -v TRASH/*
 echo "*** Creating backup at '$BACKUP' ***"
 sudo zip -rv "$BACKUP" \
 	/etc /var/{log,mail,spool} /srv /boot \
-	/usr/local/etc $EXTRA
+	/usr/local/etc $EXTRA \
+	-x /srv/backup
 status="$?"
 
 if [[ "$status" != 0 ]]; then