          data = {
              'form-TOTAL_FORMS': '3',
              'form-INITIAL_FORMS': '1',
              'form-MAX_NUM_FORMS': '0',
              'form-0-id': six.text_type(poet.id),
              'form-0-name': 'test',
              'form-1-id': '',
              'form-1-name': 'x' * 1000,  # Too long
              'form-2-id': six.text_type(poet.id),  # Violate unique constraint
              'form-2-name': 'test2',
 
</s> remove             'form-2-id': six.text_type(poet.id),  # Violate unique constraint
 </s> add             'form-2-id': str(poet.id),  # Violate unique constraint </s> remove             'form-0-id': six.text_type(poet.id),
 </s> add             'form-0-id': str(poet.id), </s> remove             'owner_set-0-auto_id': six.text_type(owner1.auto_id),
 </s> add             'owner_set-0-auto_id': str(owner1.auto_id), </s> remove             'membership_set-0-date_joined': six.text_type(now.strftime('%Y-%m-%d %H:%M:%S')),
            'initial-membership_set-0-date_joined': six.text_type(now.strftime('%Y-%m-%d %H:%M:%S')),
 </s> add             'membership_set-0-date_joined': now.strftime('%Y-%m-%d %H:%M:%S'),
            'initial-membership_set-0-date_joined': now.strftime('%Y-%m-%d %H:%M:%S'), </s> remove             'membership_set-0-date_joined_0': six.text_type(now.strftime('%Y-%m-%d')),
            'membership_set-0-date_joined_1': six.text_type(now.strftime('%H:%M:%S')),
            'initial-membership_set-0-date_joined': six.text_type(now.strftime('%Y-%m-%d %H:%M:%S')),
 </s> add             'membership_set-0-date_joined_0': now.strftime('%Y-%m-%d'),
            'membership_set-0-date_joined_1': now.strftime('%H:%M:%S'),
            'initial-membership_set-0-date_joined': now.strftime('%Y-%m-%d %H:%M:%S'),
            'form-0-id': str(poet.id),
          data = {
              'form-TOTAL_FORMS': '3',
              'form-INITIAL_FORMS': '1',
              'form-MAX_NUM_FORMS': '0',
            'form-0-id': str(poet.id),
              'form-0-name': 'test',
              'form-1-id': '',
              'form-1-name': 'x' * 1000,  # Too long
              'form-2-id': six.text_type(poet.id),  # Violate unique constraint
              'form-2-name': 'test2',
keep keep keep keep replace keep keep keep keep keep
 Refs #23919 -- Removed six.<various>_types usage

Thanks Tim Graham and Simon Charette for the reviews. 
tests/model_formsets/tests.py