Fix Rack::Utils.set_cookie_header! and delete_cookie_header! escaping

fix_cookies_escaping.rb

class << Rack::Utils
  alias_method :escape_with_plus, :escape

  def escape_without_plus(s)
    URI.encode_www_form_component(s).gsub('+', '%20')
  end

  def mock_escape_for_cookies
    singleton_class.send :alias_method, :escape, :escape_without_plus
    yield
  ensure
    singleton_class.send :alias_method, :escape, :escape_with_plus
  end

  [:set_cookie_header!, :delete_cookie_header!].each do |name|
    new_name = "#{name}_with_plus".to_sym
    alias_method new_name, name
    define_method name do |*args|
      mock_escape_for_cookies do
        send new_name, *args
      end
    end
  end
end