(and use the /accounts/email/ page (provided by allauth) instead)

'User.email' should never be updated directly

The rationale is that we rely on allauth for verifying e-mail addresses.
Allauth manages user's email addresses independently (one to many), and
updates User.email when one of these addresses is promoted to the
'primary' status. We will have less friction if we embrace the allauth
way of managing e-mails.

The good point is that allauth will never mark as primary an email
addresse that has not been verified.