[1.8.x] Fixed #24983 -- Clarified contrib.sites Site.domain is fully qualified.
[1.8.x] Fixed #24983 -- Clarified contrib.sites Site.domain is fully qualified.

Backport of 34047b23e284fd3459903294a5776b67c3e33ed9 from master

h4r5h1t/django-hauthy,h4r5h1t/django-hauthy,pquentin/django,pquentin/django,h4r5h1t/django-hauthy,pquentin/django,h4r5h1t/django-hauthy