Opening and resaving this spreadsheet causes it to become corrupt
*Created originally on Bitbucket by [dbereznyi (Daniel Bereznyi)](https://bitbucket.org/%7Be3f92b15-8c89-4d88-bd50-25c4d7670f50%7D/)*
Just doing
```
#!python
import openpyxl as xl
wb = xl.load_workbook("sheet.xlsx")
wb.save("sheet_out.xlsx")
```
causes sheet_out.xlsx to be saved incorrectly with Excel 2016 reporting the file as being corrupt. The file is opened correctly by LibreOffice 6.0.0.3 (x64). Validating sheet_out.xlsx in Open XML SDK 2.5 Productivity Tool generates this: 
*Attachments:* [sheet.xlsx](/uploads/271db515081657a109cef2836b409573/sheet.xlsx)
issue