svoid mergeJars_fileFilter(L<File> in, File out, F1<S, Bool> filter) ctex {
  ZipOutputStream zip = newZipOutputStream(out);
  new Set<S> set;
  for (File f : unnull(in))
    zip2zip_exceptManifest3(f, zip, set, filter);
  zip.close();
  print("Wrote " + fileInfo(out));
}