title: file exists but fopen "failed to open stream no such file or directory"
body: <p>It's a really strange problem.</p>
  
  <pre><code>$file = '/home/wwwroot/website/web/modules/homegrid/css/bootstrap-carousel.min.css';
  clearstatcache();
  var_dump(file_exists($file));//output true
  var_dump(is_file($file));//output true
  var_dump(is_dir($file));//output false
  var_dump(is_readable($file));//output true
  var_dump(is_writable($file));//output true
  var_dump(fopen($file, 'w+'));//output false
  var_dump(file_put_contents($file, 'asdfasdf'));//output false
  </code></pre>
  
  <p>fopen and file_put_contents always false, but file exists.
  In php 5.6 and php-fpm</p>