Matt: oops, I completely forgot about that additional patch, thanks for reminding.
Mike: to avoid FTBFS with tzdata >= 2016g, you'll also need a patch from 1.16.0-1... It was named 1001_adapt-to-timezone-namechange-for-Asia-Yangon.patch. Since it's removed now (upstream 1.16.1 already includes it), here's upstream patch link just in case: https://github.com/mate-desktop/libmateweather/commit/f8005a60b7bdd03bab3241d42cfdb06e24eb7346.patch