lisp/org-agenda.el: Prevent wrong scrolling

* lisp/org-agenda.el (org-agenda-later): Prevent window from
scrolling to the point when `scroll-conservatively' is > 101.

Reported-by: Gustavo Barros <gusbrs.2016@gmail.com>
Link: https://orgmode.org/list/87lfh2hk4k.fsf@gmail.com/

lisp/org-agenda.el

@@ -8311,7 +8311,8 @@ When optional argument BACKWARD is set, go backward."
 With prefix ARG, go forward that many times the current span."
   (interactive "p")
   (org-agenda-check-type t 'agenda)
-  (let* ((args (get-text-property (min (1- (point-max)) (point)) 'org-last-args))
+  (let* ((wstart (window-start))
+         (args (get-text-property (min (1- (point-max)) (point)) 'org-last-args))
 	 (span (or (nth 2 args) org-agenda-current-span))
 	 (sd (or (nth 1 args) (org-get-at-bol 'day) org-starting-day))
 	 (greg (calendar-gregorian-from-absolute sd))
@@ -8344,7 +8345,8 @@ With prefix ARG, go forward that many times the current span."
 	  (org-agenda-overriding-arguments
 	   (list (car args) sd span)))
       (org-agenda-redo)
-      (org-agenda-find-same-or-today-or-agenda cnt))))
+      (org-agenda-find-same-or-today-or-agenda cnt))
+    (set-window-start nil wstart)))
 
 (defun org-agenda-earlier (arg)
   "Go backward in time by the current span.