Based on a bug report (https://bitbucket.org/openpyxl/openpyxl/issues/1266/locale) from a user of the openpyxl library I've identified a bug in the zipfile module that causes the Python process to crash on Windows. Currently tested with Python 3.7.3 (32-bit on Windows 10).

Sample code

import faulthandler
import locale
from zipfile import ZipFile

faulthandler.enable()

locale.setlocale(locale.LC_ALL, 'de_DE')
out = open("out.zip", "wb") 
archive = ZipFile(out, "w")
archive.writestr("properties.xml", b"<workbookPr/>")

faulthandler fingers line 1757 as the culprit but running this line locally does not cause the crash. The issue seems to be limited to Windows.