title: openpyxl won't save if the file is opening?
body: <p>THis is my code:</p>
  <pre><code>filePath = 'D:/test/test01.xlsx'
  wb = load_workbook(filePath)
  source = wb['Template']     
  target = wb.copy_worksheet(source)
  wb.save(filePath)
  </code></pre>
  <p>I am trying to copy a worksheet named Template in the same workbook, if the file is opening, this script doesn't work and give an error &quot;permissionError:[Errno 13] Permission denied: 'D:/test/test01.xlsx'&quot;. But if I close the xlsx file, this all works fine. why this happened?</p>