svoid deleteLocalMechListCopiesOtherThan(Set<S> names) {
  for (File f : listFilesWithExtension(remoteMechListMirrorsDir(), ".name")) {
    S name = loadTextFile(f);
    if (!names.contains(name))
      deleteFiles(f, remoteMechListMirrorFile(name), remoteMechListMirrorMetaFile(name));
  }
}