PG 9.3 complains about specified more than once ??? Those views worked in PG 9.1 + 9.2

Hi,

*I ran into a major problem when I tried to import a backup from 9.1.
into a 9.3 PG.*

I just installed PG 9.3 on a new linux box.
Then I wanted to import a plaintext dump of a DB that was created by
pg_dump of PG 9.1

There are a lot of views that have joins to a subquery in the from-clause.

something like

SELECT ... some columns ...
FROM
maintable AS m
JOIN someflag AS f ON m.flag_1_id = f.id
LEFT JOIN
(
child_table AS c
JOIN someotherflag AS f ON c.flag_2_id = f.id
) AS x ON m.id = x.main_id

This works with PG 9.1 and PG 9.2 but PG 9.3 complains:

ERROR: table name "f" specified more than once

*Are there no separate namespaces for subqueries anymore in PG 9.3 ?*

Do I have to change ALL those views in the old PG 9.1 server before I
can import the backup into 9.3 or is there another way to work around
this issue ?