Rails找不到异常通知插件

$ script/plugin install git://github.com/rails/exception_notification.git

$ ls vendor/plugins/
exception_notification

$ cat vendor/plugins/exception_notification/init.rb 
require "action_mailer"
require "exception_notifier"
require "exception_notifiable"
require "exception_notifier_helper"

$ script/console
Loading development environment (Rails 2.3.2)
/usr/local/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/active_support \
  /dependencies.rb:443:in `load_missing_constant':NameError: \
  uninitialized constant ExceptionNotifier
/usr/local/lib/ruby/gems/1.8/gems/activesupport-2.3.2/lib/active_support \
  /dependencies.rb:443:in `load_missing_constant':NameError: \
  uninitialized constant ApplicationController

>> require "exception_notifier"
MissingSourceFile: no such file to load -- exception_notifier

可能很明显,但我今天很累。