MDEV-18896 Crash in convert_join_subqueries_to_semijoins : Correction

This patch complements the original patch for MDEV-18896 that prevents
conversions to semi-joins in tableless selects used in INSERT statements
in post-5.5 versions of the server.
The test case was corrected as well to ensure that potential conversion
to jtbm semi-joins is also checked (the problem was that one of
the preceeding testcases in subselect_sj.test did not restore the
state of the optimizer switch leaving the 'materialization' in the state
'off' and so blocking this check).
Noticed an inconsistency in the state of select_lex::table_list used
in INSERT statements and left a comment about this.

2 files changed, 2 insertions, 0 deletions

diff --git a/mysql-test/r/subselect_sj.result b/mysql-test/r/subselect_sj.result
index 73c620b2973..d0b8b626ba2 100644
--- a/mysql-test/r/subselect_sj.result
+++ b/mysql-test/r/subselect_sj.result
@@ -3181,6 +3181,7 @@ drop table t1,t2,t3;
 #
 # MDEV-18896: IN subquery in WHERE of a table-less query used for INSERT
 #
+set @@optimizer_switch= @subselect_sj_tmp;
 create table t1 (a1 varchar(25));
 create table t2 (a2 varchar(25)) ;
 insert into t1 select 'xxx' from dual where 'xxx' in (select a2 from t2);
diff --git a/mysql-test/r/subselect_sj_jcl6.result b/mysql-test/r/subselect_sj_jcl6.result
index 03cf368f32c..e9a8b7301f7 100644
--- a/mysql-test/r/subselect_sj_jcl6.result
+++ b/mysql-test/r/subselect_sj_jcl6.result
@@ -3195,6 +3195,7 @@ drop table t1,t2,t3;
 #
 # MDEV-18896: IN subquery in WHERE of a table-less query used for INSERT
 #
+set @@optimizer_switch= @subselect_sj_tmp;
 create table t1 (a1 varchar(25));
 create table t2 (a2 varchar(25)) ;
 insert into t1 select 'xxx' from dual where 'xxx' in (select a2 from t2);