CC Ryan Lane. Talked to him about this on IRC last week, and he thinks we shouldn't use Cache-Control here.

I think a cookie is probably a better idea, specifically a session cookie.

That said, I'm not directly working on this part of the codebase, so if someone comes up with a good solution, and the privacy implications are discussed with the community, any solution is good with me.

From the ops side, this isn't causing any real performance impacts.

Done http://wikitech.wikimedia.org/index.php?title=Server_admin_log&action=historysubmit&diff=30033&oldid=30032