patch 7.4.2314
Problem:    No error when deleting an augroup while it's the current one.
Solution:   Disallow deleting an augroup when it's the current one.
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 7d786c8..f05a55f 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -182,13 +182,17 @@
   doautocmd VimEnter
   redir END
   call assert_true(match(res, "W19:") < 0)
+  au! VimEnter
 endfunc
 
 func Test_augroup_deleted()
-  " This caused a crash
+  " This caused a crash before E936 was introduced
   augroup x
+    call assert_fails('augroup! x', 'E936:')
+    au VimEnter * echo
+  augroup end
   augroup! x
-  au VimEnter * echo
-  au VimEnter
+  call assert_true(match(execute('au VimEnter'), "-Deleted-.*VimEnter") >= 0)
+  au! VimEnter
 endfunc