title: Openpyxl does not close Excel workbook in read only mode
body: <p>I want to be able to read an Excel file in Python, keep the Python script running doing something else after the reading is finished, and be able to edit the Excel file in another process in the meantime. I'm using python 2.7 and openpyxl.</p>
  
  <p>Currently it looks like:</p>
  
  <pre><code>from openpyxl import load_workbook
  
  def get_excel_data():
      OESwb = load_workbook(filename = OESconfigFile, data_only=True, 
                            read_only=True)
      ws = OESwb.get_sheet_by_name('MC01')
      aValue = ws['A1'].value
      return aValue
  
  val = get_excel_data()
  </code></pre>
  
  <p>After I run the function, the Excel file is still locked for access from other processes  (it gives the error "'filename' is currently in use. Try again later") even when I do not want to read it in Python anymore.</p>
  
  <p>How can I close the file from my script? I've tried OESwb.close() but it gives the error "'Workbook' object has no attribute 'close'". I found <a href="https://stackoverflow.com/questions/11214908/closing-files-in-openpyxl/11215839#11215839">this post</a> but it doesn't seem to be helping.</p>
  
  <p>EDIT:
  It appears OESwb.save('filename.xlsx') works, but only if read_only=False. However, it would be ideal to be able to close the file and still be in readonly mode.  It appears this is a bug with openpyxl since it should close the file after load_workbook is finished.</p>