Action caching broken

[bgreenlee]

I spent a couple hours banging my head against the wall trying to figure out why our action caching wasn't working, until I came across this: http://www.neeraj.name/blog/articles/863-action-caching-in-broken-in-plugin-cache_fu

I applied the suggested fix and it seems to work, although I'm not sure if it breaks anything else (tests don't pass for me even before the fix).

(We're on Rails 2.2.2)