vim-patch:8.0.1414: accessing freed memory in :lfile.

Problem:    Accessing freed memory in :lfile.
Solution:   Get the current window after executing autocommands. (Yegappan
            Lakshmanan, closes vim/vim#2473)
14a4deb064

src/nvim/testdir/test_quickfix.vim

@@ -3312,3 +3312,10 @@ func Test_ll_window_ctx()
   enew | only
 endfunc
 
+" The following test used to crash vim
+func Test_lfile_crash()
+  sp Xtest
+  au QuickFixCmdPre * bw
+  call assert_fails('lfile', 'E40')
+  au! QuickFixCmdPre
+endfunc