title: django warning urls.W005 URL namespace isn't unique
body: <p>I am having trouble understanding the following warning. I have a namespace called "v1" and I am using these namespaces to determine versioning in my API (using django rest framework). So, I have paths like these:</p>
  
  <pre><code>/v1/accounts/me
  /v1/listings
  </code></pre>
  
  <p>Here is the URLs configuration (project/urls.py):</p>
  
  <pre><code>urlpatterns = [
      path('admin/', admin.site.urls),
      path('v1/accounts/', include('accounts.urls', namespace='v1')),
      path('v1/listings/', include('listings.urls', namespace='v1'))
  ]
  </code></pre>
  
  <p>accounts/urls.py</p>
  
  <pre><code>app_name = 'accounts'
  
  urlpatterns = [
      url(r'^token/$', views.obtain_auth_token, name='obtain_token'),
      url(r'^me/$', my_account, name='my_account'),
  ]
  </code></pre>
  
  <p>listings/urls.py</p>
  
  <pre><code>app_name = 'listings'
  
  urlpatterns = [
      path('', recent_listings, name='recent_listings')
  ]
  </code></pre>
  
  <p>Everything works as expected. All urls are dispatched. Versioning works. However, I keep getting the following error:</p>
  
  <blockquote>
    <p>?: (urls.W005) URL namespace 'v1' isn't unique. You may not be able to reverse all URLs in this namespace</p>
  </blockquote>
  
  <p>I know it is a warning and I might be able to suppress it; however, I want to understand why this is happening. Based on my URLconf and this warning, it seems like there cannot be multiple namespaced paths as "siblings." They need to be children of one namespaced path (e.g "v1"). If my understanding is correct, how am I supposed to create this URL configuration.</p>