protected static function setup_test_install_directory(&$test_install_request, $remove_old_files = false)
 {
     $identifier = $test_install_request->test_profile->get_identifier();
     pts_file_io::mkdir($test_install_request->test_profile->get_install_dir());
     if ($remove_old_files) {
         // Remove any (old) files that were installed
         $ignore_files = array('pts-install.xml', 'install-failed.log');
         foreach ($test_install_request->get_download_objects() as $download_object) {
             $ignore_files[] = $download_object->get_filename();
         }
         pts_file_io::delete($test_install_request->test_profile->get_install_dir(), $ignore_files);
     }
     pts_file_io::symlink(pts_core::user_home_directory() . '.Xauthority', $test_install_request->test_profile->get_install_dir() . '.Xauthority');
     pts_file_io::symlink(pts_core::user_home_directory() . '.drirc', $test_install_request->test_profile->get_install_dir() . '.drirc');
 }