# File lib/bundler/bundle.rb, line 127
    def prune(options = {})
      dependencies, sources = @environment.dependencies, @environment.sources

      sources = only_local(sources)
      bundle = Resolver.resolve(dependencies, [@cache] + sources)
      @cache.gems.each do |name, specs|
        specs.each do |spec|
          unless bundle.any? { |s| s.name == spec.name && s.version == spec.version }
            Bundler.logger.info "Pruning #{spec.name} (#{spec.version}) from the cache"
            FileUtils.rm @cache_path.join("#{spec.full_name}.gem")
          end
        end
      end
    end