upgrade to primary fails to authenticate user (intermittent)

[edwindotcom]

Over the weekend I saw this sequence. I've not seen it before and my browser doesn't block third-party cookies (to my knowledge).

1. Go to https://login.persona.org/ and click Sign Out
2. Go to a URL authenticated by mod_authn_persona (I'm unsure if this is part of the issue or not, but this was what I was attempting)
3. Click Sign in with your email
4. Type in a @mozilla.com email address
5. Your taken to a screen that says "user@mozilla.com no longer requires an extra password. Verify your account and you will immediately be signed in to example.com" user@mozilla.com no longer requires an extra password. Verify your account and you will immediately be signed in to example.com

1. Click "Verify"
2. Your taken to MozIDP : https://login.mozilla.org/sign_in?email=user%40mozilla.com
3. Login to MozIDP

1. Error message : Cannot verify jdoe@mozilla.com This may be due to your browser blocking third-party cookies. Please ensure your browser's privacy preferences are set to accept third-party cookies for mozilla.com and try again

[karlht]

After a discussion with Gene, we determined that this is probably an issue with mod_auithm_persona rather than explicitly with vinz-clortho. @lloyd, can you set me up mod_authn_persona or mod_browserid environment that I can try to replicate this in? Gene's environment has been torn down already.

Assigning to @lloyd until I have an environment to test in; feel free to hand it back to me after that.