# File lib/chef/cookbook/synchronizer.rb, line 41
    def cleanup_file_cache
      unless Chef::Config[:solo]
        # Delete each file in the cache that we didn't encounter in the
        # manifest.
        cache.find(File.join(%w{cookbooks ** *})).each do |cache_filename|
          unless @valid_cache_entries[cache_filename]
            Chef::Log.info("Removing #{cache_filename} from the cache; it is no longer needed by chef-client.")
            cache.delete(cache_filename)
          end
        end
      end
    end