def METHOD_NAME(templateFn, langFn, newFn):
    templatePo = parseFile(templateFn)
    langPo = parseFile(langFn)
    if not checkSourceMatch(templatePo, langPo, langFn):
        sys.exit(2)
    langPo.metadata['Project-Id-Version'] = "Spacewalk"
    # Get original version
    try:
        repo.index.checkout(langFn, force=True)
    except git.exc.CheckoutError as e:
        print "%s: git.exc.CheckoutError" % langFn
        return
    # Load currend HEAD version of translation file
    oldLangPo = parseFile(langFn)
    # First, filter all obsolete entries in new file if there are any
    for item in langPo.obsolete_entries():
        langPo.remove(item)
    # And now copy obsoletes from old file
    # Zanata files do not have them
    for item in oldLangPo.obsolete_entries():
        langPo.append(item)
    langPo.save(newFn)