old_contents: from django.db import models
  
  
  class PrefetchUserManager(models.Manager):
      def get_queryset(self):
          return super(PrefetchUserManager, self).get_queryset().prefetch_related('user')
  
new_contents: from django.db import models
  
  
  class PrefetchUserManager(models.Manager):
      def get_queryset(self):
          return super(PrefetchUserManager, self).get_queryset().select_related('user')
  
subject: Update managers.py