table elimination an a chain of left joins

drop table if exists t1, t2, t3;

create table t1 (id int, key (id));

insert t1 values (1),(2);

create table t2 (t1_id int primary key, id int, key (id));

insert t2 values (1,1),(2,2);

create table t3 (t2_id int primary key);

insert t3 values (1),(2);

set sql_quote_show_create=0;

explain extended select t1.id from t1 left join

    t2 on t1.id = t2.t1_id left join t3 on t2.id = t3.t2_id;