query plan optimizer bug

Hi,

it's obviously there is a query plan optimizer bug, if int2 type used in fields,
the plan generator just use sequence scan, it's stupid, i am using PG7.03,
this is my log file:
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stock# drop table a;
DROP
stock# create table  a(i int2, j int);
CREATE
stock# create unique index idx_a on a(i, j);
CREATE
stock# explain select * from a where i=1 and j=0;
psql:test.sql:4: NOTICE:  QUERY PLAN:

Seq Scan on a  (cost=0.00..25.00 rows=1 width=6)

EXPLAIN
stock# drop table a;
create table  a(i int, j int);
CREATE
stock# create unique index idx_a on a(i, j);
CREATE
stock# explain select * from a where i=1 and j=0;
psql:test.sql:8: NOTICE:  QUERY PLAN:

Index Scan using idx_a on a  (cost=0.00..2.02 rows=1 width=8)

EXPLAIN
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