i18n: do not abuse msgstr of "DEPRECATED" to check for bad translation Because 44cc9f63a2f1 requires the msgstr of "(DEPRECATED)", old *.po files must be blamed. Using "DEPRECATED" would just hide the error. For example, "LANG=da_DK.UTF-8 hg help serve" fails to hide deprecated options right now, but check-translation.py couldn't detect it because da.po has outdated translation of "DEPRECATED".