Create New Users Database Transaction

[F0rcey]

Okay, so might be a bit of an edge case, but someone else might stumble into the same issue as me.
I'm using this (great) library to add Single Sign On Functionality to a Taiga Kanban Board, which is based on Django.
Taiga sets the user e-mail as unique and non nullable (at least in it's Django Model).
I have the setting "CREATE_NEW_USERS" set to true, so that new employees can login without having to manually create a user with their username.

Problem: if a user with the same mail already exists in the DB, create_new_users creates an empty user (only username is set), and commits it to the Database, before remaining attributes, groups and flags are set.
This also means that, if there is a user in the Database without a mail set and mails have to be unique, creation of new users will always fail, since the creation of users is not in a single database transaction, but rather creates them in 4 single steps (user, attributes, groups, flags).

Creation of new users should be in a single database transaction, so that valid users can be created without running into this issue.