docs: protected FilePath findPullUpDirectory(FilePath root) throws IOException, InterruptedException {
          // if the directory just contains one directory and that alone, assume that's the pull up subject
          // otherwise leave it as is.
          List<FilePath> children = root.list();
          if(children.size()!=1)    return null;
          if(children.get(0).isDirectory())
              return children.get(0);
          return null;
      }