patch 8.2.2472: crash when using command line window in an autocommand

Problem:    Crash when using command line window in an autocommand.
            (houyunsong)
Solution:   Save and restore au_new_curbuf.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index cb5c62f..8ccc753 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -2739,9 +2739,9 @@
   au BufNew,BufWinLeave * e %e
   file yyy
   au BufNew,BufWinLeave * ball
-  call assert_fails('n xxx', 'E143:')
+  n xxx
 
-  bwipe %
+  %bwipe
   au! BufNew
   au! BufWinLeave
 endfunc
@@ -2759,4 +2759,19 @@
   augroup END
 endfunc
 
+" Fuzzer found some strange combination that caused a crash.
+func Test_autocmd_normal_mess()
+  augroup aucmd_normal_test
+    au BufLeave,BufWinLeave,BufHidden,BufUnload,BufDelete,BufWipeout * norm 7q/qc
+  augroup END
+  o4
+  silent! H
+  e xx
+  normal G
+
+  augroup aucmd_normal_test
+    au!
+  augroup END
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab