From b00211a5513a546271c4b40853df50af7cceba70 Mon Sep 17 00:00:00 2001
From: Jan Edmund Lazo <janedmundlazo@hotmail.com>
Date: Mon, 25 Jun 2018 11:31:50 -0400
Subject: [PATCH] vim-patch:8.0.0704: problems with autocommands when opening
 help

Problem:    Problems with autocommands when opening help.
Solution:   Avoid using invalid "varp" value.  Allow using :wincmd if buffer
            is locked. (closes vim/vim#1806, closes vim/vim#1804)
https://github.com/vim/vim/commit/163095f088a7c29710a16c75bb56229dd3b4116a
---
 src/nvim/ex_cmds.lua | 2 +-
 src/nvim/option.c    | 4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/nvim/ex_cmds.lua b/src/nvim/ex_cmds.lua
index c87e3d4c66..31776a70e7 100644
--- a/src/nvim/ex_cmds.lua
+++ b/src/nvim/ex_cmds.lua
@@ -3076,7 +3076,7 @@ return {
   },
   {
     command='wincmd',
-    flags=bit.bor(NEEDARG, WORD1, RANGE, NOTADR),
+    flags=bit.bor(NEEDARG, WORD1, RANGE, NOTADR, CMDWIN),
     addr_type=ADDR_WINDOWS,
     func='ex_wincmd',
   },
diff --git a/src/nvim/option.c b/src/nvim/option.c
index ed845df416..50c172b580 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -3243,6 +3243,10 @@ did_set_string_option (
         did_filetype = true;
         apply_autocmds(EVENT_FILETYPE, curbuf->b_p_ft,
                        curbuf->b_fname, true, curbuf);
+        // Just in case the old "curbuf" is now invalid
+        if (varp != &(curbuf->b_p_ft)) {
+          varp = NULL;
+        }
       }
     }
     if (varp == &(curwin->w_s->b_p_spl)) {