title: setDestinationInExternalPublicDir and getExternalStorageDirectory not equal
body: <p>In my app, I want download a zip file and unzip it.</p>
  
  <p>In <code>DownloadManager</code> request I use this:</p>
  
  <pre><code>request.setDestinationInExternalPublicDir("/SingingStudio", "file.zip");
  </code></pre>
  
  <p>This is write file in external storage.</p>
  
  <p>And when I want to access file:</p>
  
  <pre><code>String szip = Environment.getExternalStorageDirectory()+File.separator+"SingingStudio"+File.separator+"file.zip";
  </code></pre>
  
  <p>This is get file from internal storage. And <code>getExternalStoragePublicDirectory("/")</code> too.</p>
  
  <p>So I can not find the file .</p>