Incorrect URL matching : Why is the following code not raising a not found error

My views looks like this

```python class ArticleView(ListView): model = ArticleSeries context_object_name = 'articles' template_name = 'website/article-view.html'

def get_queryset(self):
    series = ArticleSeries.objects.all()
    return get_list_or_404(series)

class ArticleSeriesView(ListView): model = Article context_object_name = 'articles' template_name = 'website/article_list.html'

def get_queryset(self):
    slug = self.kwargs['article_series_slug']
    articles = Article.objects.filter(article_series__article_series_slug=slug)
    return get_list_or_404(articles)

class ArticleDetailView(DetailView): model = Article template_name = 'website/article_detail.html' context_object_name = 'article' slug_field = 'article_slug' slug_url_kwarg = 'article_slug'

def get_object(self, queryset=None):
    slug = self.kwargs.get('article_slug')
    return get_object_or_404(Article, article_slug=slug)

```

/r/django Thread Parent