Program: 53205
Project: 53205
Buggy source:
@VisibleForTesting ImmutableList<Step> buildSteps(){
  ImmutableList.Builder<Step> allSteps=ImmutableList.builder();
  if (resources.isEmpty()) {
    return allSteps.build();
  }
  String targetPackageDir=javaPackageFinder.findJavaPackage(target);
  for (  SourcePath rawResource : resources) {
    final Path pathToResource=resolver.getPath(rawResource);
    String resource=MorePaths.pathWithUnixSeparators(pathToResource);
    Matcher matcher;
    if ((matcher=GENERATED_FILE_PATTERN.matcher(resource)).matches()) {
      resource=matcher.group(1);
    }
    Path javaPackageAsPath=javaPackageFinder.findJavaPackageFolder(Paths.get(resource));
    Path relativeSymlinkPath;
    if ("String_Node_Str".equals(javaPackageAsPath.toString())) {
      relativeSymlinkPath=pathToResource.getFileName();
    }
 else {
      int lastIndex=resource.lastIndexOf(MorePaths.pathWithUnixSeparators(javaPackageAsPath));
      if (lastIndex < 0) {
        Preconditions.checkState(rawResource instanceof BuildTargetSourcePath,"String_Node_Str",pathToResource,javaPackageAsPath);
        relativeSymlinkPath=Paths.get(String.format("String_Node_Str",targetPackageDir,targetPackageDir.isEmpty() ? "String_Node_Str" : "String_Node_Str",resolver.getPath(rawResource).getFileName()));
      }
 else {
        relativeSymlinkPath=Paths.get(resource.substring(lastIndex));
      }
    }
    Path target=outputDirectory.resolve(relativeSymlinkPath);
    MkdirAndSymlinkFileStep link=new MkdirAndSymlinkFileStep(pathToResource,target);
    allSteps.add(link);
  }
  return allSteps.build();
}

Fixed version (ground truth):
@VisibleForTesting ImmutableList<Step> buildSteps(){
  ImmutableList.Builder<Step> allSteps=ImmutableList.builder();
  if (resources.isEmpty()) {
    return allSteps.build();
  }
  String targetPackageDir=javaPackageFinder.findJavaPackage(target);
  for (  SourcePath rawResource : resources) {
    final Path pathToResource=resolver.getPath(rawResource);
    String resource=MorePaths.pathWithUnixSeparators(pathToResource);
    Matcher matcher;
    if ((matcher=GENERATED_FILE_PATTERN.matcher(resource)).matches()) {
      resource=matcher.group(1);
    }
    Path javaPackageAsPath=javaPackageFinder.findJavaPackageFolder(Paths.get(resource));
    Path relativeSymlinkPath;
    if ("String_Node_Str".equals(javaPackageAsPath.toString())) {
      relativeSymlinkPath=pathToResource.getFileName();
    }
 else {
      int lastIndex=resource.lastIndexOf(MorePaths.pathWithUnixSeparatorsAndTrailingSlash(javaPackageAsPath));
      if (lastIndex < 0) {
        Preconditions.checkState(rawResource instanceof BuildTargetSourcePath,"String_Node_Str",pathToResource,javaPackageAsPath);
        relativeSymlinkPath=Paths.get(String.format("String_Node_Str",targetPackageDir,targetPackageDir.isEmpty() ? "String_Node_Str" : "String_Node_Str",resolver.getPath(rawResource).getFileName()));
      }
 else {
        relativeSymlinkPath=Paths.get(resource.substring(lastIndex));
      }
    }
    Path target=outputDirectory.resolve(relativeSymlinkPath);
    MkdirAndSymlinkFileStep link=new MkdirAndSymlinkFileStep(pathToResource,target);
    allSteps.add(link);
  }
  return allSteps.build();
}