7.0.3: order by func in union

PostgreSQL 7.0.3 on sparc-sun-solaris2.6, compiled by gcc 2.95.2

drop table tryam;
create table tryam (x text);
insert into tryam values ('22');
insert into tryam values ('1');

test=# select x from tryam union select x from tryam;x  
----221
(2 rows)

test=# select x from tryam union select x from tryam order by x;x  
----122
(2 rows)

test=# select x from tryam union select x from tryam order by length(x);x  
----122122
(4 rows)

???

Vadim