Server crashes in in my_strcasecmp_utf8 on subquery in ORDER BY clause of GROUP_CONCAT

CREATE TABLE t1 (f1 VARCHAR(10)) ENGINE=MyISAM;

INSERT INTO t1 VALUES ('a'),('b');

CREATE TABLE t2 (f2 VARCHAR(10)) ENGINE=MyISAM;

INSERT INTO t2 VALUES ('c');

CREATE TABLE t3 (f3 VARCHAR(10)) ENGINE=MyISAM;

INSERT INTO t3 VALUES ('d'),('e');

SELECT GROUP_CONCAT( f2 ORDER BY ( f2 IN ( SELECT f1 FROM t1 WHERE f1 <= f2 ) ) ) AS field 

FROM ( SELECT * FROM t2 ) AS sq2, t3 

ORDER BY field;

#3  <signal handler called>

#4  0x0000000000d1a83f in my_strcasecmp_utf8 (cs=0x1551240, s=0x7fa0ef9309e0 "f2", t=0x0) at 5.5/strings/ctype-utf8.c:2836

#5  0x00000000005e0400 in find_item_in_list (find=0x7fa0ef938ea8, items=..., counter=0x7fa0f03b42f4, report_error=REPORT_EXCEPT_NOT_FOUND, resolution=0x7fa0f03b42f0) at 5.5/sql/sql_base.cc:7260

#6  0x0000000000696089 in find_order_in_list (thd=0x7fa0f0950060, ref_pointer_array=0x7fa0efa88fc8, tables=0x7fa0ef92f078, order=0x7fa0efa88b30, fields=..., all_fields=..., is_group_field=false) at 5.5/sql/sql_select.cc:20475

#7  0x000000000069646d in setup_order (thd=0x7fa0f0950060, ref_pointer_array=0x7fa0efa88fc8, tables=0x7fa0ef92f078, fields=..., all_fields=..., order=0x7fa0efa88b30) at 5.5/sql/sql_select.cc:20585

#8  0x0000000000896e6f in Item_func_group_concat::setup (this=0x7fa0efa88b90, thd=0x7fa0f0950060) at 5.5/sql/item_sum.cc:3506

#9  0x0000000000897bb2 in Aggregator_simple::setup (this=0x7fa0ef938fa8, thd=0x7fa0f0950060) at 5.5/sql/item_sum.h:668

#10 0x00000000006a1424 in Item_sum::aggregator_setup (this=0x7fa0efa88b90, thd=0x7fa0f0950060) at 5.5/sql/item_sum.h:507

#11 0x0000000000698d1d in setup_sum_funcs (thd=0x7fa0f0950060, func_ptr=0x7fa0ef931008) at 5.5/sql/sql_select.cc:21636

#12 0x00000000006683cf in JOIN::init_execution (this=0x7fa0ef92fce0) at 5.5/sql/sql_select.cc:1899

#13 0x0000000000669ffd in JOIN::exec (this=0x7fa0ef92fce0) at 5.5/sql/sql_select.cc:2402

#14 0x000000000066c4ed in mysql_select (thd=0x7fa0f0950060, rref_pointer_array=0x7fa0f0953cd0, tables=0x7fa0ef92f078, wild_num=0, fields=..., conds=0x0, og_num=1, order=0x7fa0ef96aff8, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7fa0ef92fcc0, unit=0x7fa0f0953380, select_lex=0x7fa0f0953a60) at 5.5/sql/sql_select.cc:3094

#15 0x0000000000662fbd in handle_select (thd=0x7fa0f0950060, lex=0x7fa0f09532d0, result=0x7fa0ef92fcc0, setup_tables_done_option=0) at 5.5/sql/sql_select.cc:319

#16 0x000000000063c1fc in execute_sqlcom_select (thd=0x7fa0f0950060, all_tables=0x7fa0ef92f078) at 5.5/sql/sql_parse.cc:4689

#17 0x00000000006353de in mysql_execute_command (thd=0x7fa0f0950060) at 5.5/sql/sql_parse.cc:2234

#18 0x000000000063ece2 in mysql_parse (thd=0x7fa0f0950060, rawbuf=0x7fa0efa87078 "SELECT GROUP_CONCAT( f2 ORDER BY ( f2 IN ( SELECT f1 FROM t1 WHERE f1 <= f2 ) ) ) AS field \nFROM ( SELECT * FROM t2 ) AS sq2, t3 \nORDER BY field", length=144, parser_state=0x7fa0f03b5620) at 5.5/sql/sql_parse.cc:5909

#19 0x0000000000632925 in dispatch_command (command=COM_QUERY, thd=0x7fa0f0950060, packet=0x7fa0f0a09061 "SELECT GROUP_CONCAT( f2 ORDER BY ( f2 IN ( SELECT f1 FROM t1 WHERE f1 <= f2 ) ) ) AS field \nFROM ( SELECT * FROM t2 ) AS sq2, t3 \nORDER BY field", packet_length=144) at 5.5/sql/sql_parse.cc:1079

#20 0x0000000000631ab1 in do_command (thd=0x7fa0f0950060) at 5.5/sql/sql_parse.cc:793

#21 0x0000000000734122 in do_handle_one_connection (thd_arg=0x7fa0f0950060) at 5.5/sql/sql_connect.cc:1266

#22 0x0000000000733be1 in handle_one_connection (arg=0x7fa0f0950060) at 5.5/sql/sql_connect.cc:1181

#23 0x0000000000b6c629 in pfs_spawn_thread (arg=0x7fa0f0971fc0) at 5.5/storage/perfschema/pfs.cc:1015

#24 0x00007fa0f6de1b50 in start_thread (arg=<optimized out>) at pthread_create.c:304

#25 0x00007fa0f509770d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112