crash/valgrind error in resolve_ref_in_select_and_group

errors in context 1 of 1:

Conditional jump or move depends on uninitialised value(s)

at: resolve_ref_in_select_and_group (item.cc:5409)

by: Item_ref::fix_fields (item.cc:7910)

by: fix_fields_if_needed (item.h:1144)

by: Item_func::fix_fields (item_func.cc:347)

by: fix_fields_if_needed (item.h:1144)

by: fix_fields_if_needed_for_scalar (item.h:1148)

by: fix_fields_if_needed_for_bool (item.h:1152)

by: JOIN::prepare (sql_select.cc:1459)

by: subselect_single_select_engine::prepare(item_subselect.cc:3895)

by: Item_subselect::fix_fields (item_subselect.cc:295)

by: fix_fields_if_needed (item.h:1144)

by: fix_fields_if_needed_for_scalar (item.h:1148)

by: fix_fields_if_needed_for_bool (item.h:1152)

by: setup_conds (sql_base.cc:8444)

by: setup_without_group (sql_select.cc:832)

by: JOIN::prepare (sql_select.cc:1407)

by: mysql_select (sql_select.cc:4958)

by: mysql_multi_update (sql_update.cc:1968)

by: mysql_execute_command (sql_parse.cc:4499)

by: mysql_parse (sql_parse.cc:8026)

drop table if exists t;

create table t (a blob,  b text ) engine=innodb;

update t  set  a =current_timestamp 

where exists 

(

 select b from  t

 where @b:=a

 having a  >  72057594037927936

);