anchor.diff:  
       useLoggingPackageAdaptor();
       await for (Like l in dbService.query<Like>().run()) {
  -      final f = pool.withResource(() => _backfillLikes(l));
  -      futures.add(f);
  +      final r = await pool.request();
  +      futures.add(() async {
  +        try {
  +          await _backfillLikes(l);
  +        } finally {
  +          r.release();
  +        }
  +      }());
       }
   
       await Future.wait(futures);
  
positive.code:       'Backfilling `packageName` on like entity for user ${l.userId} and package'
        ' ${l.package}');
    try {
      await dbService.withTransaction((Transaction tx) async {
        final like = await tx.lookupValue<Like>(l.key, orElse: () => null);
        if (like == null) {
          return;
        }
        like.packageName ??= like.package;
        tx.queueMutations(inserts: [like]);
        await tx.commit();
        print('Updated packageName on like entity for user ${like.userId} and '
            'package ${like.package}');
      });
    } catch (e) {
      print('Failed to update packageName on ike entity for user ${l.userId} and '
          'package ${l.package}, error $e');
    }
  }
  
negative.code: // Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
  // for details. All rights reserved. Use of this source code is governed by a
  // BSD-style license that can be found in the LICENSE file.
  
  import 'dart:async';
  
  import 'package:appengine/appengine.dart';
  import 'package:args/args.dart';
  