DjangoGirls/tutorial — pull request #155 by Markush2010 (2014-10-30 11:03:15+00:00)
Title: Use lazy evaluated ForeignKey references to prevent future problems

Starting with Django 1.7 there have been multiple people hitting #django
with problems that eventually could be solved using lazy references to
related models instead of class references. Teaching it this ways seems
to be a good way to prevent future issues.