-Make show_explain.test stable

- Fix st_select_lex::set_explain_type() to allow producing exactly the 
  same EXPLAINs as it did before. SHOW EXPLAIN output may produce 
  select_type=SIMPLE instead or select_type=PRIMARY or vice versa (which
  is ok because values of select_type weren't self-consistent in this 
  regard to begin with)

1 files changed, 4 insertions, 1 deletions

diff --git a/sql/opt_subselect.cc b/sql/opt_subselect.cc
index 6c5e177fe1d..f8b6f80eb14 100644
--- a/sql/opt_subselect.cc
+++ b/sql/opt_subselect.cc
@@ -1346,7 +1346,8 @@ static bool convert_subq_to_sj(JOIN *parent_join, Item_in_subselect *subq_pred)
     while ((ifm= li++))
       parent_lex->ftfunc_list->push_front(ifm);
   }
-
+  
+  parent_lex->have_merged_subqueries= TRUE;
   DBUG_RETURN(FALSE);
 }
 
@@ -1458,6 +1459,8 @@ static bool convert_subq_to_jtbm(JOIN *parent_join,
   create_subquery_temptable_name(tbl_alias, hash_sj_engine->materialize_join->
                                               select_lex->select_number);
   jtbm->alias= tbl_alias;
+
+  parent_lex->have_merged_subqueries= TRUE;
 #if 0
   /* Inject sj_on_expr into the parent's WHERE or ON */
   if (emb_tbl_nest)