Last modified: 2013-10-18 20:18:53 UTC
This is deprecated according to * https://www.mediawiki.org/w/index.php?title=Manual:Messages_API&diff=645440&oldid=645435 * https://www.mediawiki.org/w/index.php?title=ResourceLoader/Default_modules&diff=780005 * http://bots.wmflabs.org/~wm-bot/logs/%23wikimedia-dev/20130909.txt so it is better to warn the users so they use the recommended methods instead.
mw.msg() is still kosher according to https://www.mediawiki.org/w/index.php?title=Manual:Messages_API&diff=785198&oldid=774570 (and TBH I agree with that personally).