[mod_python] Servlets, cookies and redirect

with mod_python servlets, I am trying to set cookie and redirect with
following code:

===========================================================
class set(HTMLPage):
    def prep(self):
        HTMLPage.prep(self)
        minute=time()+60
        self.add_cookie('test', 'test_value', expires=minute)
        self.external_redirect(view)
===========================================================

With external_redirect cookie is not set, without redirect it works fine
(cookie set). I've obviously missed something... what is a proper way to do
this?

tx,
mike