BUG #4336: Strange behaviour for to_ascii

The following bug has been logged online:

Bug reference:      4336
Logged by:          Maxime Carbonneau
Email address:      manitou@maikan.com
PostgreSQL version: 8.3.3
Operating system:   Mac OS X 10.5.4
Description:        Strange behaviour for to_ascii
Details:

With PostgreSQL 8.2.5, I used to_ascii to remove accents:
SELECT TO_ASCII(CONVERT('école' USING utf8_to_iso_8859_15), 'latin9');
=> ecole
With PostgreSQL 8.3.3, I had to made some changes since convert using is
gone. I'm using: SELECT
to_ascii(encode(convert_to('école','LATIN9'),'escape'),'LATIN9');
but the result is
=> \351cole

How can I remove accent letter with PostgreSQL 8.3.3?