title: Two slugs in one URL pattern
body: <p>How can I put two slugs in one url pattern? I have a model Link with a many to one relationship with a model category.</p>
  <pre><code>url(
      regex=r'^(?P&lt;category_slug&gt;[\w-]+)/(?P&lt;pk&gt;\d+)(?:/(?P&lt;slug&gt;[\w\d-]+))?/$',
      view=views.LinkDetailView.as_view(),
      name='link_detail'
  ),
  </code></pre>
  <p>Right now two slugs is working. But is accepting whatever you write in the category_slug section of the url.</p>
  <p>Let's say: You write 127.0.0.1:8000/there_is_no_name_like_that_in_the_database/pk/slug this. You are going to this page but there is no category with this name. I don't know why it's doing this.</p>
  <h1>links/views.py</h1>
  <pre><code>class LinkDetailView(FormMixin, DetailView):
      model = Link
      context_object_name = 'link'
      form_class = CommentForm
      success_url = reverse_lazy('home')
      def get_context_data(self, **kwargs):
          context = super(LinkDetailView, self).get_context_data(**kwargs)
          content_type = ContentType.objects.get_for_model(Link)
          obj_id = self.kwargs['pk']
          context['comments'] = Comment.objects.filter(content_type=content_type, object_id = obj_id)
          context['comment_form'] = CommentForm(initial={
                                                      'content_type': self.object.get_content_type,
                                                      'object_id': self.object.id
                                                      })
          category = Link._meta.get_field('category').rel.to
          context['uni_kabile'] = category.objects.all()
          return context
  
          ...
  </code></pre>