Users where eduPersonScopedAffiliation is a string can't sign in
Sometimes AAI returns the field as a string, sometimes as a list of strings. As we expect it to always be a list of strings, we do not permit login using unexpected profile data. The standard says it's a multi
value: https://wiki.refeds.org/display/STAN/eduPerson+2020-01#eduPerson202001-eduPersonScopedAffiliation
@thomas.beermann AAI team has been notified, keeping this here as a reminder.