I corrupted a workbook by setting a bad validation range

Created originally on Bitbucket by zvirack (Zvi Rackover)

Not sure if this is a user error, a bug or a feature request.

I am using the latest released package.

The following code corrupted my workbook. The problem was that the column letters were in lower case.

#!python

decimal = DataValidation(type="decimal")
decimal.ranges.append("c2:e14")
ws.add(decimal)
...
Save the workbook

Next time i loaded the workbook using openpyxl, an exception was raised after the regex which expects upper-case range letters failed.

So if this is not a user error, i suggest that openpyxl will either fail when entering a range which does not match the regex or use a more robust regex allowing lower-case column letters.

Thanks