Confirming an email address throws an unexpected error when already confirmed via Persona

[François Marier]

When a user clicks a confirmation link for an email that has already been confirmed using Persona, an error page is displayed due to a database uniqueness constraint violation:

  File "/usr/share/libravatar/libravatar/account/views.py", line 93, in confirm_email
    not request.user.is_anonymous())

  File "/usr/share/libravatar/libravatar/account/models.py", line 243, in create_confirmed_email
    confirmed.save()

  IntegrityError: ERREUR: la valeur d'une clé dupliquée rompt la contrainte unique « account_confirmedemail_email_key »

Steps to reproduce:

1- create a new username+password account
2- add a new email address manually (but don't check your emails yet)
3- add a new email address but this time, use Persona to add the same one
4- go back to the profile page to see that email address both under "confirmed" and "unconfirmed" emails
5- click on the link sent in the confirmation email

[François Marier (fmarier)]

Three things to fix:

1. the unconfirmed email should be deleted before we attempt to confirm the email to ensure that any bugs further down the function don't leave unconfirmed emails around
2. before creating a confirmed email object, check that it's not already confirmed. if it is, display an appropriate error message
3. confirming an email using Persona should delete any matching unconfirmed emails that a user has in their account

[François Marier (fmarier)]

Deleting the unconfirmed email is tricky so I've skipped that. Otherwise, it's fixed on master.