Bug in pg_get_ruledef?

Hello,

pg_get_ruledef cannot read the following rule:

test=# select version();
version
---------------------------------------------------------------------
PostgreSQL 7.2b3 on i686-pc-linux-gnu, compiled by GCC egcs-2.91.66
(1 row)

With the following tables:

test=# \d rd
Table "rd"
Column | Type | Modifiers
--------+----------+-----------
a | smallint |
b | smallint |
c | text |

Table "ri"
Column | Type | Modifiers
--------+----------+--------------
d | smallint |
e | text |
a | smallint | default 1000
b | smallint | default 2000

I create the following rule:

CREATE RULE ins_rd
AS ON INSERT TO ri
WHERE NEW.a IS NOT NULL
AND NEW.b IS NOT NULL
DO
INSERT INTO rd (a,b)
select distinct new.a,new.b

The rule works well. But when i select pg_rules:

test=# select * from pg_rules;
ERROR: Invalid attnum 3 for rangetable entry *SELECT*

Thanks in advance

Sergio.