ASP: set safe defaults for disable_and_create_empty_persistence_conf_file

Will-fix: #15802

config/chroot_local-includes/usr/local/sbin/live-persist

@@ -260,6 +260,11 @@ disable_and_create_empty_persistence_conf_file ()
 	local conf="$1"
 	local mode="$2"
 
+	if [ -z "$mode" ]
+	then
+		mode=0600
+	fi
+
 	mv "$conf" "${conf}.insecure_disabled" \
 		|| error "Failed to disable '$conf': $?"
 	create_empty_persistence_conf_file "$conf" "$mode"