Django backends.py not 100% identical (1.11 vs 2.2)

[TravelTimN]

https://docs.djangoproject.com/en/2.2/topics/auth/customizing/

Backends for Django2.2 doesn't allow either username or email address when logging in.
Apparently only username is accepted, so need to figure out how to get both working again.

LMS:
Authentication & Authorisation > Custom Authentication > Email Authentication