Fixed a bug in merge.

sql/sql_handler.cc

@@ -426,8 +426,6 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
   {
     if (table->query_id != thd->query_id)
       cond->cleanup();                          // File was reopened
-    if ((!cond->fixed &&
-	 cond->fix_fields(thd, tables, &cond)) || cond->check_cols(1))
     goto err0;
   }