anchor.diff:      }, cancelOnError: cancelOnError);
       _subscriptions.add(subscription);
     }
  +
  +  /// Return a human-friendly string representation of [event].
  +  String _formatEvent(FileSystemEvent event) {
  +    if (event == null) return 'null';
  +
  +    var path = p.relative(event.path, from: directory);
  +    var type = event.isDirectory ? 'directory' : 'file';
  +    if (event is FileSystemCreateEvent) {
  +      return "create $type $path";
  +    } else if (event is FileSystemDeleteEvent) {
  +      return "delete $type $path";
  +    } else if (event is FileSystemModifyEvent) {
  +      return "modify $type $path";
  +    } else if (event is FileSystemMoveEvent) {
  +      return "move $type $path to "
  +          "${p.relative(event.destination, from: directory)}";
  +    }
  +  }
  +
  +  // TODO(nweiz): remove this when the buildbots calm down.
  +  /// Whether this code is running on a buildbot.
  +  bool get _runningOnBuildbot =>
  +    Platform.environment.containsKey('BUILDBOT_BUILDERNAME');
   }
  
positive.code: 
  import 'dart:async';
  import 'dart:io';
  
  import '../constructable_file_system_event.dart';
  import '../path_set.dart';
  
negative.code:     var fileExists = new File(path).existsSync();
      var dirExists = new Directory(path).existsSync();
  
      if (_runningOnBuildbot) {
        print("file existed: $fileExisted");
        print("dir existed: $dirExisted");
        print("file exists: $fileExists");
        print("dir exists: $dirExists");
      }
  
      var events = [];
      if (fileExisted) {
        if (fileExists) {
  