Odd 'except' and 'default' interaction behavior

We noticed a strange behavior involving 'except' and 'default'
interaction. Example from psql:

wpbb=# \d robtest
Table "robtest"
Attribute | Type | Modifier
-----------+---------+-------------
id | integer | default '1'
userid | integer |
articleid | integer |

wpbb=# insert into robtest (userid,articleid) select '1'::int4,'2'::int4 except select '2'::int4,'5'::int4;
ERROR: Each UNION | EXCEPT | INTERSECT query must have the same number of columns.

wpbb=# alter table robtest alter column id drop default;
ALTER

wpbb=# insert into robtest (userid,articleid) select '1'::int4,'2'::int4 except select '2'::int4,'5'::int4;
INSERT 306530 1

Notice that error regarding the usage of except and the # of columns.
Strange. Yet, that exact same query works fine when we remove a
default on a column on the table which isn't being referenced.

I'm not sure if this is a bug, a poorly written error message, or my
ignorance. :') We are using Postgresql 7.0.3 release under Linux:

phil=# select version();
version
----------------------------------------------------------------
PostgreSQL 7.0.3 on i686-pc-linux-gnu, compiled by gcc 2.7.2.3 (1 row)

Thanks!!

Phil

--
Philip Edelbrock -- IS Manager -- Edge Design, Corvallis, OR
phil(at)netroedge(dot)com -- http://www.netroedge.com/~phil
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