[ Edit: I no longer need an answer to this question. ] All translators — Did anyone have a locale.php file (like ru_RU.php) in 3.3 that they no longer included in 3.4? If so, what is your locale? Those files are going to sit there (and be included) after an upgrade, so we need to remove them manually: http://core.trac.wordpress.org/ticket/20974. Unfortunately it is not easy to ascertain which locales used to have them but no longer do.