private function fetchLastCommitTimes()
  {
    // Execute command for get list with file name and mtime from GIT log
    $command = "git log --format='format:%ai' --name-only";
    exec($command, $output, $return);
    if ($return!=0) $this->logError("Can not execute command %s in exec", $command);

    // Find latest mtime for each file from $output.
    // Note: Each line is either:
    //       * an empty line
    //       * a timestamp
    //       * a filename.
    $commit_date = '';
    foreach ($output as $line)
    {
      if ((preg_match('/^\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2} [+\-]\d{4}$/', $line)))
      {
        $commit_date = strtotime($line);
      }
      else if ($line!=='')
      {
        $filename = $line;
        if (isset($this->myLastCommitTimes[$filename]) && $this->myLastCommitTimes[$filename]<$commit_date)
        {
          $this->myLastCommitTimes[$filename] = $commit_date;
        }
      }
    }
  }