Django allauth social login: automatically linking social site profiles using the registered email

Note (2018-10-23): I’m not using this anymore. Too much magic happening. Instead I enabled SOCIALACCOUNT_EMAIL_REQUIRED and 'facebook': { 'VERIFIED_EMAIL': False, ... }. So allauth will redirect social logins on a social signup form to enter a valid email address. If it’s already registered an error shows up to login first and then connect the account. Fair enough for me atm.

I’m trying to improve this kind of use case and came up with the following solution:

from allauth.account.models import EmailAddress
from allauth.socialaccount.adapter import DefaultSocialAccountAdapter

class SocialAccountAdapter(DefaultSocialAccountAdapter):
    def pre_social_login(self, request, sociallogin):
        """
        Invoked just after a user successfully authenticates via a
        social provider, but before the login is actually processed
        (and before the pre_social_login signal is emitted).

        We're trying to solve different use cases:
        - social account already exists, just go on
        - social account has no email or email is unknown, just go on
        - social account's email exists, link social account to existing user
        """

        # Ignore existing social accounts, just do this stuff for new ones
        if sociallogin.is_existing:
            return

        # some social logins don't have an email address, e.g. facebook accounts
        # with mobile numbers only, but allauth takes care of this case so just
        # ignore it
        if 'email' not in sociallogin.account.extra_data:
            return

        # check if given email address already exists.
        # Note: __iexact is used to ignore cases
        try:
            email = sociallogin.account.extra_data['email'].lower()
            email_address = EmailAddress.objects.get(email__iexact=email)

        # if it does not, let allauth take care of this new social account
        except EmailAddress.DoesNotExist:
            return

        # if it does, connect this new social login to the existing user
        user = email_address.user
        sociallogin.connect(request, user)

As far as I can test it, it seems to work well. But inputs and suggestions are very welcome!