Duplicate user issue when using social auth

[sentry-io[bot]]

Sentry Issue: FLAGSMITH-API-4Q3

FFAdminUser.MultipleObjectsReturned: get() returned more than one FFAdminUser -- it returned 2!
(13 additional frame(s) were not displayed)
...
  File "custom_auth/views.py", line 42, in post
    serializer.is_valid(raise_exception=True)
  File "users/models.py", line 93, in get_by_natural_key
    return self.get(email__iexact=email)

It seems as though it is possible to create duplicate (when evaluated case insensitively) email addresses in the database by authenticating first with email password.

Based on example, it seems that the steps to reproduce this issue are:

1. Register (using email and password) with an email address using all lower case e.g. billy.the.kid@gmail.com
2. Register (using Google) with the same email address but with certain characters capitalised, e.g. Billy.The.Kid@gmail.com

[khvn26]

I guess CIEmailField is not an option given the continued Oracle support?

[matthewelwell]

I guess CIEmailField is not an option given the continued Oracle support?

Correct.