write status file only if parent dir exists

mysql_backup.sh

@@ -34,5 +34,5 @@ while read uh; do mysql --defaults-file=${defaultfile} -BNe "show grants for $uh
 if [ $error -eq 0 ] ; then
    find $rdir  -maxdepth 1 -type d -mtime +${rotate} -exec rm -fr {} \;
 fi
-echo $error > $status_file
+test -d ${status_file%/*} && echo $error > $status_file
 exit $error