class Bundler::Installer

def local_index
  @local_index ||= begin
    index = Index.new
    sources.each do |source|
      next unless source.respond_to?(:local_specs)
      index = source.local_specs.merge(index)
    end
    index = Index.from_installed_gems.merge(index)
    if File.directory?("#{root}/vendor/cache")
      index = cache_source.specs.merge(index).freeze
    end
    Index.from_cached_specs("#{Bundler.bundle_path}/cache").merge(index)
  end
end