# File lib/bundler/runtime.rb, line 83
    def cache
      FileUtils.mkdir_p(cache_path)

      Bundler.ui.info "Updating .gem files in vendor/cache"
      specs.each do |spec|
        next if spec.name == 'bundler'
        spec.source.cache(spec) if spec.source.respond_to?(:cache)
      end
      prune_cache unless Bundler.settings[:no_prune]
    end