Make sure we do not get an IntegrityError because we are trying to create a new user with the same username as already created by another factory.

src/utils/factories.py

@@ -5,6 +5,7 @@ from factory.django import DjangoModelFactory
 class UserFactory(DjangoModelFactory):
     class Meta:
         model = 'auth.User'
+        django_get_or_create = ('username',)
 
     username = factory.Faker('word')
     email = factory.Faker('ascii_email')