title: Are django signals also included inside of the transaction.atomic decorator?
body: <p>I have a model file that uses a <code>post_save</code> signal to create a linked row in another table. In typical fashion, I can create a page from one of my views which is decorated with @transaction.atomic.</p>
  
  <p>I would like to know if this decorator will put the creation of the Page object and the SharedPage object in the same transaction. It is not clear from the django docs that signals are a part of this atomic transaction.</p>
  
  <p><strong>models.py</strong></p>
  
  <pre><code>class Page(models.Model):
      name = models.CharField(default='My default page',max_length=200,blank=False)
      created_at = models.DateTimeField(auto_now_add=True)
      owner = models.ForeignKey(User, on_delete=models.CASCADE)
      slug = models.SlugField()
      uuid = models.UUIDField(default=uuid.uuid4, editable=False)
      is_public = models.BooleanField(default=False)
  
      def __str__(self):              # __unicode__ on Python 2
          return self.name
  
      class Meta:
          ordering = ['position','created_at']
  
  @receiver(post_save, sender=Page)
  def create_shared_page_entry(sender, instance, created, **kwargs):
      if created:
          shared_page = SharedPage.objects.create(
              page=instance,
              user=instance.user,
              can_edit=True
          )
  </code></pre>
  
  <p><strong>view.py</strong></p>
  
  <pre><code>@require_http_methods(["POST"])
  @transaction.atomic
  def page_create(request):
      name = request.POST.get('name')
      page = Page.objects.create(name=name, owner=request.user)
  
      data = serializers.serialize("json", [page])
      return HttpResponse(data, content_type='application/json')
  </code></pre>