is this a bug or I am blind?

online=# select * from common_logins where username = 'potyty';
uid | username | password | lastlogin | status | usertype | loginnum
-----+----------+----------+-----------+--------+----------+----------
(0 rows)

online=# select * from common_logins where username like 'potyty';
uid | username | password | lastlogin | status |
usertype | loginnum
--------+----------+----------+----------------------------+--------+----------+----------
155505 | potyty | board | 2004-08-16 17:45:55.723829 | A |
S | 1
60067 | potyty | board | 2004-07-07 20:22:17.68699 | A |
S | 3
174041 | potyty | board | 2005-02-17 00:00:13.706144 | A |
S | 3
(3 rows)

online=# select username, username = 'potyty' from common_logins where
username like 'potyty';
username | ?column?
----------+----------
potyty | t
potyty | t
potyty | t
(3 rows)

psql 8.0.3, Debian.

Mage