Unable to delete last column on Windows

Created originally on Bitbucket by osnownoy (Andrew Kisel)

Today I noticed some weird issue that for some reason last column in my file (and any test file I created with similar structure) is not being deleted with 'delete_cols()'. Any other column is deleted fine. The files I tested on Windows were created on Windows machines.

Code that I used for testing on both Windows and Mac:

#!python

wb = openpyxl.load_workbook('Test_data.xlsx')
ws = wb.active
ws.delete_cols(5)
wb.save('Test.xlsx')

On Windows it simply does not change anything and on Mac it removes any column just fine.

I use Python 3.6.3 on Windows and Python 3.6.2 on Mac.

Attachments: File_After_MacFile_Before_Mac