Single logout should raise on request failure

[beheh]

Right now, a network failure during remote logout (as part of SLO) will be silently ignored by mama_cas. It seems crucial that a logout failure is raised or at least returned so that the user can take appropriate action, like retry or refuse to logout.

Specifically, ServiceTicket.request_sign_out will blindly session.post without looking at the response.

django-mama-cas/mama_cas/models.py

Lines 248 to 257 in 03935d9

	def request_sign_out(self, session=requests):
	"""
	Send a POST request to the ``ServiceTicket``s logout URL to
	request sign-out.
	"""
	if logout_allowed(self.service):
	request = SingleSignOutRequest(context={'ticket': self})
	url = get_logout_url(self.service) or self.service
	session.post(url, data={'logoutRequest': request.render_content()})
	logger.info("Single sign-out request sent to %s" % url)

This should probably raise on at least some very severe network errors, like timeouts or internal server errors.

I'm not sure how this plays with the requests-futures support, but it seems like mama_cas should at least expose a way to do this if you really want to.

[zxbzxb180]

Excuse me, why does my request_sign_out not execute?