crash in insert select with sub query

Test case:
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);
drop table t1,t2;

Causes convert_subq_to_jtbm() at:
for (tl= (TABLE_LIST*)(parent_lex->table_list.first); tl->next_local; tl= tl->next_local)

Because parent_lex->table_list.first is 0