patch 8.2.1059: crash when using :tabonly in an autocommand

Problem:    Crash when using :tabonly in an autocommand. (Yegappan Lakshmanan)
Solution:   Do not allow the autocommand window to be closed.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index d7328c3..446d22b 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -2617,7 +2617,27 @@
     au!
   augroup END
   augroup! aucmd_win_test2
-  %bw!
+  %bwipe!
+endfunc
+
+" Test for trying to close the tab that has the temporary window for exeucing
+" an autocmd.
+func Test_close_autocmd_tab()
+  edit one.txt
+  tabnew two.txt
+   augroup aucmd_win_test
+    au!
+    au BufEnter * if expand('<afile>') == 'one.txt' | tabfirst | tabonly | endif
+  augroup END
+
+  call assert_fails('doautoall BufEnter', 'E813:')
+
+  tabonly
+  augroup aucmd_win_test
+    au!
+  augroup END
+  augroup! aucmd_win_test
+  %bwipe!
 endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab