class HTTP::Response::Caching

def body=(new_body)
  @body = if new_body.respond_to?(:readpartial) && new_body.respond_to?(:read)
            # IO-ish, probably a rack cache response body
            IoBody.new(new_body)
          elsif new_body.respond_to? :join
            # probably an array of body parts (rack cache does this sometimes)
            StringBody.new(new_body.join(""))
          elsif new_body.respond_to? :readpartial
            # normal body, just use it.
            new_body
          else
            # backstop, just to_s it
            StringBody.new(new_body.to_s)
          end
end