qbs clean crashes after occupying all available memory when a artifact lies outside the build directory

  Artifact {
   fileTags:  ['hpp', 'rpc_header_file']
   fileName:  { return RpcFuncs.headerFilePath(input.fileName); }
  }

 
void ArtifactCleaner::cleanup(const TopLevelProjectPtr &project, 
         const QList<ResolvedProductPtr> &products, const CleanOptions &options)
...
    // Directories created during the build are not artifacts (TODO: should they be?),
    // so we have to clean them up manually.
    QList<QString> dirList = directories.toList();
    for (int i = 0; i < dirList.count(); ++i) {
        const QString &dir = dirList.at(i);
        if (dir.startsWith(project->buildDirectory) && FileInfo(dir).exists())
            removeEmptyDirectories(dir, options);
        if (dir != project->buildDirectory) {
            const QString parentDir = QDir::cleanPath(dir + "/..");
   /* -> */ if (parentDir != project->buildDirectory && !dirList.contains(parentDir))
                dirList << parentDir;
        }
    }
....