static File findFileWithSameContents(S path) {
  ret findFileWithSameContents(newFile(path));
}

static File findFileWithSameContents(File f) {
  for (File f2 : listFilesOnly(dirOfFile(f)))
    if (!isSameFile(f, f2) && filesHaveSameContents(f, f2))
      ret f2;
  null;
}