uninitialized read in Item_cond::fix_fields leads to crash: select .. where .. in ( select ... )

drop table if exists `t1`;

create table `t1`(`a` char(1) character set utf8)engine=innodb;

select 1 from `t1` where `a` in (select group_concat(`a`) from t1);

Version: '10.0.0-MariaDB-log'  socket: ''  port: 3306  Source distribution

121228  7:46:33 [ERROR] mysqld got exception 0xc0000005 ;

mysqld.exe!setup_jtbm_semi_joins()[opt_subselect.cc:5224]

mysqld.exe!JOIN::optimize_inner()[sql_select.cc:1123]

mysqld.exe!JOIN::optimize()[sql_select.cc:992]

mysqld.exe!mysql_select()[sql_select.cc:3176]

mysqld.exe!handle_select()[sql_select.cc:362]

mysqld.exe!execute_sqlcom_select()[sql_parse.cc:4937]

mysqld.exe!mysql_execute_command()[sql_parse.cc:2421]

mysqld.exe!mysql_parse()[sql_parse.cc:6061]

mysqld.exe!dispatch_command()[sql_parse.cc:1219]

mysqld.exe!do_command()[sql_parse.cc:951]

mysqld.exe!threadpool_process_request()[threadpool_common.cc:225]

mysqld.exe!io_completion_callback()[threadpool_win.cc:568]