'This method should not be overwritten by any plugin (but you are free
to do it, for example a good idea is to rewrite this method to change
the UrlOpener to do some IDS evasion technique).
This method takes a CustomUrllib object as parameter and assigns it
to itself. Then, on the testUrl method you use
self.CustomUrlOpener._custom_urlopen(...)
to open a Url and you are sure that the plugin is using the user
supplied settings (proxy, user agent, etc).
:return: No value is returned.'

def set_url_opener(self, url_opener):

    self._uri_opener = UrlOpenerProxy(url_opener, self)
