fixes 1033849 - debug persona login

@rhelmer (cc @AdrianGaudebert) r?

It's not pretty but it's potentially super useful to people struggling with login.
![screenshot 2014-07-02 16 59 42](https://cloud.githubusercontent.com/assets/26739/3464040/006594b0-0245-11e4-8da6-43c99fe00b2c.png)

I agree this doesn't have to be perfect, and don't mind if we merge as is. I was curious if that was something generally accepted in the django world, because it looks confusing and hard to read / debug to me. But yes, in this case it's fine.