patch 9.0.1309: scrolling two lines with even line count and 'scrolloff' set
Problem: Scrolling two lines with even line count and 'scrolloff' set.
Solution: Adjust how the topline is computed. (closes #10545)
diff --git a/src/proto/move.pro b/src/proto/move.pro
index 00b4d29..0858e26 100644
--- a/src/proto/move.pro
+++ b/src/proto/move.pro
@@ -43,7 +43,7 @@
void scroll_cursor_top(int min_scroll, int always);
void set_empty_rows(win_T *wp, int used);
void scroll_cursor_bot(int min_scroll, int set_topbot);
-void scroll_cursor_halfway(int atend);
+void scroll_cursor_halfway(int atend, int prefer_above);
void cursor_correct(void);
int onepage(int dir, long count);
void halfpage(int flag, linenr_T Prenum);