update sandbox line detection

plugins/localdump/mysql.sh

@@ -100,8 +100,7 @@ function mysql.db.import(){
 
   # https://mariadb.org/mariadb-dump-file-compatibility-change/
   # if sandbox mode is detected then skip the first line
-  local sSandbox; sSandbox='/*!999999\- enable the sandbox mode */'
-  if zcat "$_dumpfile" | head -1 | grep -Fq "$sSandbox" 
+  if zcat "$_dumpfile" | head -1 | grep -Fq '!999999\- enable the sandbox mode'
   then
     zcat "$_dumpfile" | tail +2 | mysql $BACKUP_PARAMS "${_dbname}"
   else