bug#27968: 26.0.50; dired-revert: Saved positions might change if a dired header changes

[Eli Zaretskii]

> From: Tino Calancha <tino.calancha@gmail.com>
> Date: Sat, 05 Aug 2017 22:01:34 +0900
> Cc: stephen berman <stephen.berman@gmx.net>
> 
> Dired headers also changes; if you add/deleted some files,
> the used space shown changes: that will mess up the saved
> buffer positions if the length of the header is different.
> 
> This problem causes dired-test-bug27243-01 to fail in hydra.
> 
> One possible solution is the patch below.  It saves line numbers
> instead of positions.  Line numbers won't change if a dired header
> changes its length.

Won't using markers be a better solution?