Unexpected ER_DUP_ENTRY upon GROUP BY query from a table with blob

create table t (a blob);

insert into t values (0),(0);

select @x := a, count(*) from t group by 1;

drop table t;

create table t (a blob);

insert into t values (0),(0);

select @x := a, count(*) from t group by 1;

bug.496-94a                              [ fail ]

        Test ended at 2026-05-23 00:29:49

CURRENT_TEST: bug.496-94a

mysqltest: At line 4: query 'select @x := a, count(*) from t group by 1' failed: ER_DUP_ENTRY (1062): Duplicate entry '0' for key 'group_key'