[V7/Trunk]Not Chinese localised login and DB menu

[Joshua Jan(SHINEIT)]

HI all,

  I found this problem in "web/controller/main.py"
def bootstrap_translations(self, mods):
 """ Load local translations from *.po files, as a temporary solution
            until we have established a valid session. This is meant only
            for translating the login page and db management chrome, using
            the browser's language. """
        # For performance reasons we only load a single translation, so for
        # sub-languages (that should only be partially translated) we load the
        # main language PO instead - that should be enough for the login screen.
        lang = request.lang.split('_')[0]
....
When the browser`s language is Chinese. The requet.lang is "zh_CN". The lang will be "zh" after split. But there is no "zh.po"
in web/i18n/

In V7 I copy the zh_CN.po to zh.po. It works. But in Trunk doesn`t work.

Best Regards
Joshua