Strange problem for nokogiri on Rails 3

Rails
1

I am test the script named test.rb by command “ruby test.rb” and it
pass.
Then i converte it as rake task.
The rake task pass on rails 2.3.4 but fail on rails 3 beta4

============================
env ：rails 3 beta4, ruby 1.8.7, ubuntu

test.rb

require ‘rubygems’
require ‘nokogiri’
require ‘open-uri’
require “iconv”

url = “http://www.bugutang.com”
doc = Nokogiri::HTML(open(url))
doc.css(“title”).each do |c|
puts Iconv.iconv(“GBK//IGNORE”, “UTF-8//IGNORE”, c.content)

end

============================
claw.rake

desc "Fetch product "
task :claw => :environment do
require ‘rubygems’
require ‘nokogiri’
require ‘open-uri’
require “iconv”

url = “http://www.bugutang.com”
doc = Nokogiri::HTML(open(url))
doc.css(“title”).each do |c|
puts Iconv.iconv(“GBK//IGNORE”, “UTF-8//IGNORE”, c.content)

end

end

gem env
RubyGems Environment:

  • RUBYGEMS VERSION: 1.3.7
  • RUBY VERSION: 1.8.7 (2008-08-11 patchlevel 72) [x86_64-linux]
  • INSTALLATION DIRECTORY: /usr/lib/ruby/gems/1.8
  • RUBY EXECUTABLE: /usr/bin/ruby1.8
  • EXECUTABLE DIRECTORY: /usr/bin
  • RUBYGEMS PLATFORMS:
    • ruby
    • x86_64-linux
  • GEM PATHS:
    • /usr/lib/ruby/gems/1.8
    • /home/bugu/.gem/ruby/1.8
  • GEM CONFIGURATION:
    • :update_sources => true
    • :verbose => true
    • :benchmark => false
    • :backtrace => false
    • :bulk_threshold => 1000
  • REMOTE SOURCES:

nokogiri (1.4.2)
Authors: Aaron P., Mike D.
Rubyforge: http://rubyforge.org/projects/nokogiri
Homepage: http://nokogiri.org
Installed at: /usr/lib/ruby/gems/1.8

How can i do ?