title: Multiple django storages
body: <p>I have a django project in which all my static and media files are stored on s3. The storage for the same is the default storage. I created another storage for my private files.</p>
  
  <pre><code>protected_storage = S3BotoStorage(
      acl='private',
      bucket=settings.IMPORT_SHEETS_BUCKET,
      querystring_auth=True,
      querystring_expire=60,
  )
  </code></pre>
  
  <p>In one of my models there is a file field.</p>
  
  <pre><code>import_sheet = models.FileField(storage=protected_storage)
  </code></pre>
  
  <p>When I upload a file to this field, it is uploaded to the required bucket. However when i try to access it from django admin, I get a url of the default storage bucket. Thoughts?</p>