anchor.diff:        file = Pathname.new("#{brew_gem_prefix}/#{gemspec.bindir}/#{exe}")
         (bin+file.basename).open('w') do |f|
           f << <<-RUBY
  -#!#{ruby_path} --disable-gems
  +#!#{BREWGEM_RUBY_PATH} --disable-gems
   ENV['GEM_HOME']="#{prefix}"
   ENV['GEM_PATH']="#{prefix}"
   require 'rubygems'
  
positive.code: 
  require 'formula'
  require 'fileutils'
  
  class RubyGemsDownloadStrategy < AbstractDownloadStrategy
    def fetch
      ohai "Fetching <%= name %> from gem source"
      HOMEBREW_CACHE.cd do
        ENV['GEM_SPEC_CACHE'] = "#{HOMEBREW_CACHE}/gem_spec_cache"
        system "gem", "fetch", "<%= name %>", "--version", resource.version
      end
    end
  
  
negative.code:     ENV['GEM_HOME']="#{prefix}"
      ENV['GEM_PATH']="#{prefix}"
  
      system BREWGEM_GEM_PATH, "install", cached_download,
               "--no-ri",
               "--no-rdoc",
               "--no-wrapper",
  