title: Django RedirectView with missing variables
body: <p>Hello I want to redirect the urls like <code>/{category}/{sub_category}</code> to <code>/{category}/</code> but RedirectView wants to resolve the url with both subcategory and category keyword arguments</p>
  
  <pre><code>url(r'^/(?P&lt;category_slug&gt;[^\/]+)/$', CategoryView.as_view(), name='category'),
  
  url(r'^/(?P&lt;category_slug&gt;[^\/]+)/(?P&lt;another_parameter&gt;[^\/]+)$',
      RedirectView.as_view(pattern_name='category')),
  </code></pre>
  
  <p>so this doesn't work, I think default should be ignoring unrequired parameters..</p>
  
  <p>I am getting <code>django.urls.exceptions.NoReverseMatch:</code></p>
  
  <p>What would be the best option to make this work?</p>