def get_header_lines(header):
    """
    Splits the header into lines, putting multi-line headers together.
    """
    r = []
    lines = header.split(b'\n')
    for line in lines:
        if line.startswith((b' ', b'\t')):
            r[-1] = r[-1] + line[1:]
        else:
            r.append(line)
    return r
