I got a report from a translation team that `make po' is not working anymore. If you run it for a second time the generated *.po file will never change. I could reproduce this myself for doc/zh_TW.UTF-8/articles/leap-seconds
The problem may be started by this commit: commit 916a887bbaf3f89f30f1920b52f9652d3d5a20c4 Author: wblock <wblock@FreeBSD.org> Date: Mon Aug 14 21:08:28 2017 +0000 Trim obsolete translations from PO files. These are translations for text which does not exist in the original English document any more. The line ${MSGATTRIB} --no-obsolete -o ${PO_LANG}.po.new ${PO_LANG}.po is using wrong parameters, it use the old *.po file as input (instead the new one) and overrides the fresh updated *.po with old data.
A commit references this bug: Author: wosch Date: Thu May 10 20:06:55 UTC 2018 New revision: 51638 URL: https://svnweb.freebsd.org/changeset/doc/51638 Log: Fix `make po' for updates PR: 227905 Differential Revision: https://reviews.freebsd.org/D15263 Changes: head/share/mk/doc.translate.mk