This bug was fixed by RMS on 2004-11-02:

This bug was fixed by RMS on 2004-11-02:

** scroll-preserve-screen-position doesn't work with a header-line-format

From: jbyler+emacs-lists@anon41.eml.cc
Date: Tue, 17 Aug 2004 17:10:14 -0400

There seems to be an off-by-one error triggered by using a header line
together with scroll-preserve-screen-position.  The symptom: instead of
staying in the same position on the screen when scrolling, the cursor
moves one screen line down each time the buffer is scrolled.  Put
another way: repeatedly typing C-v M-v or using a mouse scroll wheel to
scroll up and down causes the cursor to migrate slowly down the screen
instead of staying put as it should.

To reproduce:

emacs -q --no-site-file
(setq scroll-preserve-screen-position t)
(setq header-line-format "")
C-v M-v C-v M-v C-v M-v etc.