SET old_mode without MYSQL50_TABLE_NAMES fails when the current database name starts with #

create database `#db`;

use `#db`;

set old_mode=MYSQL50_TABLE_NAMES;

set old_mode=default;

show warnings;

select @@old_mode;

use test;

set old_mode=default;

drop database `#db`;

13.2.0-MariaDB-asan-debug-log source revision: dc266b6ff7610fbb10b00c86be47b9c7e86670e0

set old_mode=default;

ERROR 42000: Variable 'old_mode' can't be set to the value of 'DEFAULT'

show warnings;

Level	Code	Message

Warning	1102	Incorrect database name '#db'

Error	1231	Variable 'old_mode' can't be set to the value of 'DEFAULT'

select @@old_mode;

@@old_mode

MYSQL50_TABLE_NAMES