The relevant code in Zope2's ZPublisher.HTTPResponse.__str__:
# ... we just built a headersl list using self.heders
if self.cookies:
headersl = headersl+self._cookie_list()
headersl[len(headersl):] = [self.accumulated_headers, body]
return '\n'.join(headersl)
Maybe this can shed some light on whether we want to include that patch.
Daniel