I wrote:
> The most expedient way to fix it seems to be to make
> has_legal_joinclause consider, not the set of all relations anywhere
> in the query, but just members of the current initial_rels list.
8.2 patch is here, if you need it now:
http://archives.postgresql.org/pgsql-committers/2008-01/msg00164.php
regards, tom lane