old_contents: from django.db import models
  from django_mailer import constants
  
  
  class QueueManager(models.Manager):
      use_for_related_fields = True
  
      def high_priority(self):
          """
          Return a QuerySet of high priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_HIGH)
  
      def normal_priority(self):
          """
          Return a QuerySet of normal priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_NORMAL)
  
      def low_priority(self):
          """
          Return a QuerySet of low priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_LOW)
  
      def non_deferred(self):
          """
          Return a QuerySet containing all non-deferred queued messages.
          
          """
          return self.filter(deferred=False)
  
      def deferred(self):
          """
          Return a QuerySet of all deferred messages in the queue.
          
          """
          return self.filter(deferred=True)
  
      def retry_deferred(self, new_priority=None):
          """
          Reset the deferred flag for all deferred messages so they will be
          retried.
          
          """
          count = self.deferred().count()
          update_kwargs = dict(deferred=False, retries=models.F('retries')+1)
          if new_priority is not None:
              update_kwargs['priority'] = new_priority
          self.deferred().update(**update_kwargs)
          return count
  
new_contents: from django.db import models
  from django_mailer import constants
  
  
  class QueueManager(models.Manager):
      use_for_related_fields = True
  
      def high_priority(self):
          """
          Return a QuerySet of high priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_HIGH)
  
      def normal_priority(self):
          """
          Return a QuerySet of normal priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_NORMAL)
  
      def low_priority(self):
          """
          Return a QuerySet of low priority queued messages.
          
          """
          return self.filter(priority=constants.PRIORITY_LOW)
  
      def non_deferred(self):
          """
          Return a QuerySet containing all non-deferred queued messages.
          
          """
          return self.filter(deferred=None)
  
      def deferred(self):
          """
          Return a QuerySet of all deferred messages in the queue.
          
          """
          return self.exclude(deferred=None)
  
      def retry_deferred(self, new_priority=None):
          """
          Reset the deferred flag for all deferred messages so they will be
          retried.
          
          """
          count = self.deferred().count()
          update_kwargs = dict(deferred=False, retries=models.F('retries')+1)
          if new_priority is not None:
              update_kwargs['priority'] = new_priority
          self.deferred().update(**update_kwargs)
          return count
  
subject: Fix the manager methods for deferred/non_deferred