page caching 30x requests

Currently, page caching caches any request w/ a status code < 400. Is
there a reason for this?

#6514 changes it to only cache 200 requests, and includes some actual
page caching tests. Thoughts?

I did something fairly similar on my one site that uses page caching

    after_filter :cache_all_pages
    def cache_all_pages
      cache_page if request.get? && response.headers['Status'] == "200
OK" && request.env['REQUEST_URI'] !~ /\?/

Your checking for a 200 status is better (since it uses to_i), but you
should only cache get requests (not sure how your code handles head
requests), and requests with URL parameters shouldn't be cached.