bug#35334: 26.2; Changes to position of point are undone during with-current-buffer if window is visible but not current

[Noam Postavsky]

>      (defun ordinary-insertion-filter (proc string)
>        (when (buffer-live-p (process-buffer proc))
>          (with-current-buffer (process-buffer proc)
>            (let ((moving (= (point) (process-mark proc))))
>              (save-excursion
>                ;; Insert the text, advancing the process marker.
>                (goto-char (process-mark proc))
>                (insert-before-markers string) ; <------------ change here
>                (set-marker (process-mark proc) (point)))
>              (if moving (goto-char (process-mark proc)))))))

If we make this update in the manual, would that sufficiently clarify
the sitatuation, or do we need anything else?