def ref_lang_po_file(self):
        """Return a parsed .po file object for the "reference language", if one
        exists, otherwise None.
        """
        ref_pofile = None
        if rosetta_settings.ENABLE_REFLANG and self.ref_lang != 'msgid':
            replacement = '{separator}locale{separator}{ref_lang}'.format(
                separator=os.sep,
                ref_lang=self.ref_lang
            )
            pattern = '\{separator}locale\{separator}[a-z]{{2}}'.format(separator=os.sep)
            ref_fn = re.sub(pattern, replacement, self.po_file_path,)
            try:
                ref_pofile = pofile(ref_fn)
            except IOError:
                # there's a syntax error in the PO file and polib can't
                # open it. Let's just do nothing and thus display msgids.
                # XXX: :-/
                pass
        return ref_pofile
Return a parsed .po file object for the "reference language", if one
        exists, otherwise None.