Overflow partition and reserved value

drop table Test_Partitioning;
drop partition scheme Test_Partition_Scheme;
drop partition function Test_Partition_Function;

create partition function Test_Partition_Function (datetime)
as range left for values (0); -- special reserved value

create partition scheme Test_Partition_Scheme
as partition Test_Partition_Function
all to ([PRIMARY]);

create table Test_Partitioning (
    id int not null,
    stamp datetime not null,
    primary key (id, stamp)
) ON Test_Partition_Scheme (stamp);

insert into Test_Partitioning values (1, '2001-01-01');
insert into Test_Partitioning values (2, 0);
insert into Test_Partitioning values (2, 1);

SELECT
    $partition.Test_Partition_Function(t.stamp) AS [Partition Number],
    t.id,
    case when t.stamp = 0 then null else t.stamp end as stamp
FROM
    Test_Partitioning t

/*
Partition Number    id  stamp
1           2   NULL
2           1   2001-01-01 00:00:00.000
2           2   1900-01-02 00:00:00.000
*/