title: WebClient.DownloadString doesn't return correct unicode charactes altough its encoding is set to UTF8
body: <pre><code>WebClient wc = new WebClient();
  wc.Encoding= System.Text.Encoding.UTF8;
  wc.DownloadStringAsync(new Uri("http://example.com/test.html"));
  </code></pre>
  
  <p>What am I doing wrong here?</p>