Just upgrading capybara from 0.3.9 to 0.4.1.2, cukes and specs fail

Using capybara (0.3.9) with steak and when running my steak acceptance spec with :js => true, firefox is fired and it works. But when I upgrade capybara to 0.4.1.2 in Gemfile and run the same spec, firefox is fired on port 9887 but the page just show Unable to connect. I think the selenium server couldn't fire. This also affects my cucumber scenarios with @javascript tag too.

Following is my spec_helper.rb

require 'spork'

Spork.prefork do
  ENV["RAILS_ENV"] ||= 'test'
  ...
  RSpec.configure do |config|
    ...
    config.before(:each, :type => :acceptance) do
      Capybara.reset_sessions!
      Capybara.default_selector = :css
      Capybara.default_driver = :selenium
      Capybara.javascript_driver = :selenium

      Capybara.current_driver = :selenium if example.metadata[:js]
    end

    config.after(:each, :type => :acceptance) do
      Capybara.use_default_driver if example.metadata[:js]
    end
  end
end

Sp开发者_开发知识库ork.each_run do
    load "#{Rails.root}/spec/Sporkfile.rb" if File.exists?("#{Rails.root}/spec/Sporkfile.rb")
end

and this is the acceptance_helper.rb

require File.expand_path(File.dirname(__FILE__) + "/../spec_helper")
require "steak"

# Put your acceptance spec helpers inside /spec/acceptance/support
Dir["#{File.dirname(__FILE__)}/support/**/*.rb"].each {|f| require f}