  
  @python_2_unicode_compatible
  class CyclicTwo(models.Model):
      name = models.CharField(max_length=25)
      one = models.ForeignKey(CyclicOne)
  
      def __str__(self):
          return self.name
  
  
 
</s> remove     two = models.ForeignKey('CyclicTwo')
 </s> add     two = models.ForeignKey('CyclicTwo', models.CASCADE) </s> remove     content_type = models.ForeignKey(ContentType)
 </s> add     content_type = models.ForeignKey(ContentType, models.CASCADE) </s> remove     network = models.ForeignKey(Network)
 </s> add     network = models.ForeignKey(Network, models.CASCADE) </s> remove     restaurant = models.ForeignKey(Restaurant)
 </s> add     restaurant = models.ForeignKey(Restaurant, models.CASCADE) </s> remove     poet = models.ForeignKey(Poet)
 </s> add     poet = models.ForeignKey(Poet, models.CASCADE)
    one = models.ForeignKey(CyclicOne, models.CASCADE)
  
  @python_2_unicode_compatible
  class CyclicTwo(models.Model):
      name = models.CharField(max_length=25)
    one = models.ForeignKey(CyclicOne, models.CASCADE)
  
      def __str__(self):
          return self.name
  
  
keep keep keep keep replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/admin_views/models.py