patch 8.2.4797: getwininfo() may get oudated values

Problem:    getwininfo() may get oudated values.
Solution:   Make sure w_botline is up-to-date. (closes #10226)
diff --git a/src/evalwindow.c b/src/evalwindow.c
index 53fd1e3..43a6d63 100644
--- a/src/evalwindow.c
+++ b/src/evalwindow.c
@@ -395,6 +395,9 @@
     if (dict == NULL)
 	return NULL;
 
+    // make sure w_botline is valid
+    validate_botline_win(wp);
+
     dict_add_number(dict, "tabnr", tpnr);
     dict_add_number(dict, "winnr", winnr);
     dict_add_number(dict, "winid", wp->w_id);
diff --git a/src/testdir/test_bufwintabinfo.vim b/src/testdir/test_bufwintabinfo.vim
index 1d8e74a..403b98a 100644
--- a/src/testdir/test_bufwintabinfo.vim
+++ b/src/testdir/test_bufwintabinfo.vim
@@ -172,4 +172,26 @@
   bw!
 endfunc
 
+func Test_getwininfo_au()
+  enew
+  call setline(1, range(1, 16))
+
+  let g:info = #{}
+  augroup T1
+    au!
+    au WinEnter * let g:info = getwininfo(win_getid())[0]
+  augroup END
+
+  4split
+  " Check that calling getwininfo() from WinEnter returns fresh values for
+  " topline and botline.
+  call assert_equal(1, g:info.topline)
+  call assert_equal(4, g:info.botline)
+  close
+
+  unlet g:info
+  augroup! T1
+  bwipe!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/version.c b/src/version.c
index 74c0832..6bed251 100644
--- a/src/version.c
+++ b/src/version.c
@@ -747,6 +747,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4797,
+/**/
     4796,
 /**/
     4795,