Confirmed users that do not have their email in the emails table

@ahegyi discovered, that there are some (at the moment 7) recent confirmed users that do not have their primary email in the emails table. Why don't know why. It might be a race condition. We should investigate. Recent change around emails happened in !70872 (merged).

Notes:

• currently the primary email is added to the emails upon calling user.confirm or directly upon user creation if the user is created "already confirmed"
• the user.confirm method overrides the Devise implementation. Confirming the primary email and adding it to the emails table is not done atomically - so one of the two can fail without the other failing.