      A model that has relation to a proxy model
      or to a proxy of proxy model
      """
      version = models.CharField(max_length=50)
      reporter = models.ForeignKey(ProxyTrackerUser)
      associated_bug = models.ForeignKey(ProxyProxyBug)
  
  
  class ProxyImprovement(Improvement):
      class Meta:
          proxy = True
 
</s> remove     item = models.ForeignKey(Item)
 </s> add     item = models.ForeignKey(Item, models.CASCADE) </s> remove     honeycomb = models.ForeignKey(Honeycomb)
 </s> add     honeycomb = models.ForeignKey(Honeycomb, models.CASCADE) </s> remove     user = models.OneToOneField(User, primary_key=True)
 </s> add     user = models.OneToOneField(User, models.CASCADE, primary_key=True) </s> remove     reporter = models.ForeignKey(BaseUser)
 </s> add     reporter = models.ForeignKey(BaseUser, models.CASCADE) </s> remove     car = models.ForeignKey(Car)
 </s> add     car = models.ForeignKey(Car, models.CASCADE)
    reporter = models.ForeignKey(ProxyTrackerUser, models.CASCADE)
    associated_bug = models.ForeignKey(ProxyProxyBug, models.CASCADE)
      A model that has relation to a proxy model
      or to a proxy of proxy model
      """
      version = models.CharField(max_length=50)
    reporter = models.ForeignKey(ProxyTrackerUser, models.CASCADE)
    associated_bug = models.ForeignKey(ProxyProxyBug, models.CASCADE)
    reporter = models.ForeignKey(ProxyTrackerUser, models.CASCADE)
    associated_bug = models.ForeignKey(ProxyProxyBug, models.CASCADE)
  
  
  class ProxyImprovement(Improvement):
      class Meta:
          proxy = True
keep keep keep keep replace replace keep keep keep keep keep
 Fixed #21127 -- Started deprecation toward requiring on_delete for ForeignKey/OneToOneField 
tests/proxy_models/models.py