遇到 cannot load such file -- rubygems/defaults/ruby

以client.rb作为参数运行ruby -d，结果遇到：

Exception `LoadError' at F:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems.rb:1273 -

cannot load such file -- rubygems/defaults/ruby

查F:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems.rb:1273
if defined?(RUBY_ENGINE) then
    begin
      ##
      # Defaults the ruby implementation wants to provide for RubyGems

#这一行
require "rubygems/defaults/#{RUBY_ENGINE}"
     rescue LoadError

http://stackoverflow.com/questions/1021216/ruby-gem-loaderror-rubygems-defaults-operating-system
google了很久，不过没什么影响。