title: Using Django's new i18n_patterns: How to fall back to the default language specified in the settings module?
body: <p>I'm using the new <code>i18n_patterns</code> of Django 1.4:</p>
  
  <pre><code>from django.conf.urls import patterns, include, url
  from django.conf.urls.i18n import i18n_patterns
  
  from django.contrib import admin
  admin.autodiscover()
  
  urlpatterns += i18n_patterns('',
      url(r'^admin/', include(admin.site.urls)),
  )
  </code></pre>
  
  <p>It works for every active language:</p>
  
  <pre><code>/en/admin/ # Ok
  /es/admin/ # Ok
  </code></pre>
  
  <p>But this fails:</p>
  
  <pre><code>/admin/ # 404 Not found
  </code></pre>
  
  <p>How to avoid the 404 error and redirect to a language-prefixed version of the requested URL (not only the admin panel)?</p>
  
  <p>Is to write a custom middleware the solution? Why this doesn't come by default in Django?</p>