Fixed #28517 -- Fixed admin delete confirmation view crash when related models don't have a delete permission.

tests/admin_views/models.py

@@ -582,6 +582,14 @@ class ReadablePizza(Pizza):
         proxy = True
 
 
+# No default permissions are created for this model and both name and toppings
+# are readonly for this model's admin.
+class ReadOnlyPizza(Pizza):
+    class Meta:
+        proxy = True
+        default_permissions = ()
+
+
 class Album(models.Model):
     owner = models.ForeignKey(User, models.SET_NULL, null=True, blank=True)
     title = models.CharField(max_length=30)