BUG #1304: update does not honor order of subselect

The following bug has been logged online:

Bug reference:      1304
Logged by:          Brendan Fagan

Email address:      bfagan@harthosp.org

PostgreSQL version: 7.3.6

Operating system:   RedHat ES 3

Description:        update does not honor order of subselect

Details:

SQL Update command does not follow the order of a WHERE field IN subselect.

In the following code, I try to reset the order of rows in a column by
updating an order field.  Update does not honor the order of output form the
subselect.

create temp sequence foo increment  1 minvalue 0 start 0;

select setval('foo', 0);

update nav_content_structure
set     nav_cannister_ord_num = nextval('foo')
where    nav_content_id in (
    select     s.nav_content_id
    from     nav_content_structure s,
        nav_content c
    where     s.nav_content_tie_id = 2624
    and     s.nav_cannister_id is not null
    and     c.nav_content_id = s.nav_content_id
    order by s.nav_cannister_id, c.nav_content_title )
and nav_content_tie_id = 2624