Thanks Tim Graham for the review.

Thanks igorcc for the report.

Thanks Zach Borboa for the report.

Thanks jwmayfield, serg.partizan, and Wojciech Banaś for work on the patch.

Thanks fwkroon for the report.

The only debatable thing here is setting FIRST_DAY_OF_WEEK to 1.
The only examples of calendars I can find in Welsh start on Monday,
for example, the calendar on S4C (the only all Welsh TV station).

http://www.s4c.co.uk/clic/c_clicschedule.shtml

Note re migrations importing custom fields

Refs #22267.

Thanks Md. Enzam Hossain for the report and initial patch, and
Tim Graham for the review.

There's always a better word.

Thanks abhillman for the suggestion and Claude Paroz for review.

Thanks jukvalim for the report and initial patch,
and Preston Timmons for review.

Thanks Graham Dumpleton for the report.

Thanks liminspace for the patch and Keryn Knight for benchmarking.

If loading an application trigger an ImportError, the details of that
error were lost in some cases. Thanks Ben Davis for the report.

This is the idiomatic word in the Python world.

This reverts commit cbbc7131.

This fixes a regression introduced by the 53ff0969 security fix.

Thanks to @a1tus for the report and Tim for the review.

refs #23329.

Thanks velle for the report.