Request: add 1 to the total messages and translated messages when an optional message is translated.
At least since 2011 (perhaps always), optional messages are not considered in statistics for how much a group is translated. This is good to avoid "falsely" reporting a group as partially untranslated when all non-optional messages are translated; but it's bad when a group is reported as fully untranslated and below the export threshold.
Case at hand: https://gerrit.wikimedia.org/r/#/c/339601/3 / eb8b6d3099e79c47397d1258770d7cc03611f762 . https://translatewiki.net/wiki/Special:LanguageStats/ang shows "pywikibot redirect" 0 % translated, i.e. 0/5, when it's actually 1/6 translated, but the one translated message is optional. https://translatewiki.net/w/i.php?title=Special:Translate&group=out-pywikipedia-redirect&language=ang&filter=&action=translate&optional=1
I believe there might have been another report about outdated/fuzzied optional messages.
Message groups with only optional messages do now get exported if other conditions are met.