makemessages overrides the *.po files even if they are already up to date

[Daniyal Abbasi]

The *.po files are updated when the makemessages command in run even if they are already up to date. The significant change that occurs is the "POT-Creation-Date". If a *.po file exists, we should use the --update flag of msgmerge. This will not update the *.po if all the translation strings are not updated.

A benifit of this (that I personally encountered) would be writing pre-commit hooks for makemessages. The pre-commit hooks would not update the file if it is already up to date.

[Daniyal Abbasi]

I created a PR for this.
​https://github.com/django/django/pull/14800

[Claude Paroz]

Makes sense. Please add a test.

[Daniyal Abbasi]

Thanks for accepting this. I'm not sure where the tests should live. Should the tests go in the BasicExtractorTests or should they be in a separate class in the tests.i18n.test_extraction?
Moreover, I could not find any tests for the write_po_file method of the makemessages Command class. Let me know how I shall proceed!

[Mariusz Felisiak]

Claude, it looks like a duplicate of #6106. IMO we should close this as a duplicate and reopen the original ticket if we want to change the previous decision.

[Claude Paroz]

This may be discussed on the django-developers mailing list.

I guess the closing 11 years ago was to keep the meaning of POT-Creation-Date as "last time we checked for new translations", vs "last time a string changed in the file". However I can understand the issue it is with source control, having been bitten by this too. Now I think I'm rather in favour of the change, but getting more opinions from the mailing list would be great.

[Mariusz Felisiak]

Duplicate of #6106.