sS disk_findMountPoint(File f, LS mountPoints) {
  ret f == null ? null : disk_findMountPoint(f.getPath(), mountPoints);
}

sS disk_findMountPoint(S f, LS mountPoints) {
  if (f == null) null;
  S path = addFileSep(getCanonicalPath(f));
  ret lowestByScoreFunction(mountPoints, mp -> startsWith(path, addFileSep(mp)) ? l(mp) : null);
}