Error with views containing sub-queries with distinct

Last night I just upgraded to a nightly snapshot of 7.4 and noticed an
error on queries that had previously worked (in version 7.3.x and
previous 7.4's snapshots up to about a month old).

I have a view that I can distill into a base case of:

CREATE VIEW testing_v AS
SELECT table_a.*
FROM table_a
WHERE
(table_a.some_id IN (
SELECT DISTINCT table_b.some_id
FROM table_b
));

When I do :

select * from testing_v;

I get:

JOIN qualification may not refer to other relations

I have found that if I remove the distinct on the sub-query, it behaves
as expected.

Yes, I know the distinct is probably useless but we are in the process
of porting it to postgres and have lots of cleanup left.

We are migrating from a commercial database (and paid good money) and
found postgres to be a joy (substantially fast, less gotchas, better at
embeding business logic at db level).

Thank you very much. I appreciate all the effort that has put into such
a great product.

--spt

PS: Please cc me as I am not on list.