Fix intermittent failure in OpenID test

This should fix the intermittent failure in master:
http://jenkins.edx.org:8080/job/edx-deploy-branch-tests/1612/testReport/?

I suspect this may also get fixed when we upgrade Django, as there's a closed issue for it: https://code.djangoproject.com/ticket/19051  I'd like to get this in anyway to avoid failures in the short term.

@jzoldak