anchor.diff:  
       // Write out the merged results for the builders.
       if (2 <= builders.length) {
  -      print("Merging downloaded results from the builders...");
         await new File("${outDirectory.path}/previous.json").writeAsString(
             mergedResults.values.map((data) => jsonEncode(data) + "\n").join(""));
         await new File("${outDirectory.path}/flaky.json").writeAsString(
             mergedFlaky.values.map((data) => jsonEncode(data) + "\n").join(""));
       }
   
  +    // Override the named configuration in the baseline data if needed.
  +    if (namedConfiguration != localConfiguration) {
  +      for (final path in [
  +        "${outDirectory.path}/previous.json",
  +        "${outDirectory.path}/flaky.json"
  +      ]) {
  +        final results = await loadResultsMap(path);
  +        final records = results.values
  +            .where((r) => r["configuration"] == namedConfiguration)
  +            .toList()
  +              ..forEach((r) => r["configuration"] = localConfiguration);
  +        await new File(path).writeAsString(
  +            records.map((data) => jsonEncode(data) + "\n").join(""));
  +      }
  +    }
  +
       // Run the tests.
       final arguments = [
  -      "--named-configuration=$namedConfiguration",
  +      "--named-configuration=$localConfiguration",
         "--output-directory=${outDirectory.path}",
         "--clean-exit",
         "--silent-failures",
  
positive.code:     return;
    }
    final namedConfiguration = namedConfigurations.single;
    for (final builder in builders) {
      print("Testing the named configuration $namedConfiguration "
          "compared with builder $builder");
    }
  
    // Find out where the current HEAD branched.
  
negative.code:       final deflakeDirectory = new Directory("${outDirectory.path}/$i");
        await deflakeDirectory.create();
        final deflakeArguments = <String>[
          "--named-configuration=$localConfiguration",
          "--output-directory=${deflakeDirectory.path}",
          "--clean-exit",
          "--silent-failures",
  