'Ensure that the operation continues if the username matches an
existing user account and the supplied email differs only in cases.'

def test_same_email_varied_case(self):

    User.objects.create(username=TEST_USERNAME, email=TEST_EMAIL.upper())
    call_command('manage_user', TEST_USERNAME, TEST_EMAIL.lower())
    user = User.objects.get(username=TEST_USERNAME)
    self.assertEqual(user.email, TEST_EMAIL.upper())
