anchor.diff:      var downloadNumber = 0;
       // Download the previous results and flakiness info from cloud storage.
       for (final builder in builders) {
  +      final builderName = builder.name;
         if (needsMerge) {
           previousFileName = "previous-$downloadNumber.json";
           flakyFileName = "flaky-$downloadNumber.json";
           downloadNumber++;
         }
  -      print("Finding build on builder $builder to compare with...");
  +      print("Finding build on builder $builderName to compare with...");
         // Use the buildbucket API to search for builds of the right commit.
         final buildSearchResult =
  -          await searchForApproximateBuild(builder, commit);
  +          await searchForApproximateBuild(builderName, commit);
         if (buildSearchResult.commit != commit) {
           print("Warning: Using commit ${buildSearchResult.commit} "
  -            "as baseline instead of $commit for $builder");
  -        inexactBuilds[builder] = buildSearchResult.commit;
  +            "as baseline instead of $commit for $builderName");
  +        inexactBuilds[builderName] = buildSearchResult.commit;
         }
         final buildNumber = buildSearchResult.build.toString();
  -      print("Downloading results from builder $builder build $buildNumber...");
  +      print("Downloading results from builder $builderName "
  +          "build $buildNumber...");
         tasks.add(cpGsutil(
  -          buildFileCloudPath(builder, buildNumber, "results.json"),
  +          buildFileCloudPath(builderName, buildNumber, "results.json"),
             "${outDirectory.path}/$previousFileName"));
         if (!options["report-flakes"]) {
           tasks.add(cpGsutil(
  -            buildFileCloudPath(builder, buildNumber, "flaky.json"),
  +            buildFileCloudPath(builderName, buildNumber, "flaky.json"),
               "${outDirectory.path}/$flakyFileName"));
         }
       }
  
positive.code:       Platform.script.resolve("../third_party/gsutil/gsutil.py").toFilePath();
  
    // Load the test matrix.
    final scriptPath = Platform.script.toFilePath();
    final testMatrixPath =
        scriptPath.substring(0, scriptPath.length - "test.dart".length) +
            "bots/test_matrix.json";
    final testMatrix = jsonDecode(await new File(testMatrixPath).readAsString());
    final branches = (testMatrix["branches"] as List).cast<String>();
    final buildersConfigurations =
        testMatrix["builder_configurations"] as List<dynamic>;
    // Determine what named configuration to run and which builders to download
    // existing results from.
    final testedConfigurations = resolveNamedConfigurations(
        branches,
        buildersConfigurations,
        options["branch"],
        requestedNamedConfigurations,
        requestedBuilder);
    if (testedConfigurations == null) {
      // No valid configuration could be found. The error has already been
      // reported by [resolveConfigurations].
  
negative.code: import 'dart:io';
  
  import 'package:args/args.dart';
  import 'package:smith/smith.dart';
  
  import 'bots/results.dart';
  
  