Oh, the sosospider. I know that one.
:: detour to most recent robot log collection ::
As of last January, the sosospider asks for robots.txt under the "wrong" hostname (always), doesn't follow-up the redirect, and never asks for anything else. That's under 126.96.36.199.
Further detour to raw logs shows that "Sosospider" disappeared abruptly near the end of March. Either they lost interest in me, or they've moved and changed their name.