module ActionDispatch::Http::Cache::Response

def initialize(*)
  status, header, body = super
  @cache_control = {}
  @etag = self["ETag"]
  if cache_control = self["Cache-Control"]
    cache_control.split(/,\s*/).each do |segment|
      first, last = segment.split("=")
      last ||= true
      @cache_control[first.to_sym] = last
    end
  end
end