SSO auth lock form authentication

[arnaud-morvan]

One user cannot login using the form authentication since he logged in pro-montagne (and c2c with SSO).
He tried the lost password procedure without success.

My first idea was that he have two different emails in pro-montagne and camptocamp, but it seems it is not the case.

I've tried to reproduce locally and on the demo with my own account, without success.

No idea what's going wrong.