Code review comment for ~pappacena/turnip:upgrade-python-openid2

Your changes themselves look OK, and python-openid2 is probably the best choice of Python-3-compatible replacements for python-openid. However, when I tried to convert Launchpad itself to it, I found that it has normalisation problems that specifically affect the OpenID identity URLs used by SSO. turnip's test suite doesn't currently exercise its OpenID handling very much (if at all?), but Launchpad's test suite picks this up, and I *think* it will affect attempting to log into turnip using SSO. I'd advise holding off on this until python-openid2 is fixed, and then upgrading to a fixed version before landing this.

See my upstream PR for more details:

  https://github.com/ziima/python-openid/pull/41