@classmethod
def _readold(cls, repo):
    """Read the old position-based version of a shelvestate file"""
    keys = [b'version', b'name', b'originalwctx', b'pendingctx', b'parents',
        b'nodestoremove', b'branchtorestore', b'keep', b'activebook']
    fp = repo.vfs(cls._filename)
    d = {}
    try:
        for key in keys:
            d[key] = fp.readline().strip()
    finally:
        fp.close()
    return d
