patch 8.2.2900: QuitPre is triggered before :wq writes the file

Problem:    QuitPre is triggered before :wq writes the file, which is
            different from other commands.
Solution:   Trigger QuitPre after writing the file. (closes #8279)
diff --git a/src/testdir/test_writefile.vim b/src/testdir/test_writefile.vim
index e4293e3..e94071f 100644
--- a/src/testdir/test_writefile.vim
+++ b/src/testdir/test_writefile.vim
@@ -915,4 +915,25 @@
   call delete('Xfile3')
 endfunc
 
+" Check that buffer is written before triggering QuitPre
+func Test_wq_quitpre_autocommand()
+  edit Xsomefile
+  call setline(1, 'hello')
+  split
+  let g:seq = []
+  augroup Testing
+    au QuitPre * call add(g:seq, 'QuitPre - ' .. (&modified ? 'modified' : 'not modified'))
+    au BufWritePost * call add(g:seq, 'written')
+  augroup END
+  wq
+  call assert_equal(['written', 'QuitPre - not modified'], g:seq)
+
+  augroup Testing
+    au!
+  augroup END
+  bwipe!
+  unlet g:seq
+  call delete('Xsomefile')
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab