title: Diagnosing QDir::rmdir failure
body: <p>I’m using the following code to delete an empty folder on Linux:</p>
  
  <pre><code>bool removeFolder (const QString&amp; path)
  {
     QDir dir(path);
     assert(dir.exists());
     return dir.rmdir(".");
  }
  </code></pre>
  
  <p>For some reason it sometimes returns false (for specific folders, but those folders don’t seem to be wrong in any way). If I subsequently use ::rmdir from <code>&lt;unistd.h&gt;</code> to remove the same folder, it succeeds. 
   How can I tell why <code>QDir::rmdir</code> is failing?</p>
  
  <p>This never happened on Windows so far, <code>QDir::rmdir</code> just works.</p>