patch 8.2.1780: statusline not updated when splitting windows

Problem:    Statusline not updated when splitting windows.
Solution:   Call status_redraw_all(). (Jason Franklin, closes #5496)

src/testdir/test_statusline.vim

@@ -433,4 +433,21 @@ func Test_statusline_removed_group()
   call delete('XTest_statusline')
 endfunc
 
+func Test_statusline_after_split_vsplit()
+  only
+
+  " Make the status line of each window show the window number.
+  set ls=2 stl=%{winnr()}
+
+  split | redraw
+  vsplit | redraw
+
+  " The status line of the third window should read '3' here.
+  call assert_equal('3', nr2char(screenchar(&lines - 1, 1)))
+
+  only
+  set ls& stl&
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1780,
 /**/
     1779,
 /**/

src/window.c

@@ -1273,13 +1273,11 @@ win_split_ins(
     if (flags & (WSP_TOP | WSP_BOT))
 	(void)win_comp_pos();
 
-    /*
-     * Both windows need redrawing
-     */
+     // Both windows need redrawing.  Update all status lines, in case they
+     // show something related to the window count or position.
     redraw_win_later(wp, NOT_VALID);
-    wp->w_redr_status = TRUE;
     redraw_win_later(oldwin, NOT_VALID);
-    oldwin->w_redr_status = TRUE;
+    status_redraw_all();
 
     if (need_status)
     {