import zipfile


def zipfile_get_file_datetime(zipfilename, fname):
    """Returns the date_time of the given file with the archive."""
    with zipfile.ZipFile(zipfilename, 'r') as zf:
        for info in zf.infolist():
            if info.filename == fname:
                return info.date_time
    
    raise Exception("Unable to find %s" % fname)