From e7d1376b636e6c758196c3542bd2c1053f9edb75 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Fri, 30 Oct 2015 14:23:33 +0100
Subject: [PATCH] patch 7.4.901 Problem:    When a BufLeave autocommand changes
 folding in a way it syncs             undo, undo can be corrupted. Solution: 
  Prevent undo sync. (Jacob Niehus)

---
 src/popupmnu.c | 10 ++++++++++
 src/version.c  |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/src/popupmnu.c b/src/popupmnu.c
index 68ee2d5623..2f5e7dc811 100644
--- a/src/popupmnu.c
+++ b/src/popupmnu.c
@@ -568,7 +568,11 @@ pum_set_selected(n, repeat)
 	    if (p_pvh > 0 && p_pvh < g_do_tagpreview)
 		g_do_tagpreview = p_pvh;
 	    ++RedrawingDisabled;
+	    /* Prevent undo sync here, if an autocommand syncs undo weird
+	     * things can happen to the undo tree. */
+	    ++no_u_sync;
 	    resized = prepare_tagpreview(FALSE);
+	    --no_u_sync;
 	    --RedrawingDisabled;
 	    g_do_tagpreview = 0;
 
@@ -659,7 +663,9 @@ pum_set_selected(n, repeat)
 			 * redraw. */
 			if (resized)
 			{
+			    ++no_u_sync;
 			    win_enter(curwin_save, TRUE);
+			    --no_u_sync;
 			    update_topline();
 			}
 
@@ -670,7 +676,11 @@ pum_set_selected(n, repeat)
 			pum_do_redraw = FALSE;
 
 			if (!resized && win_valid(curwin_save))
+			{
+			    ++no_u_sync;
 			    win_enter(curwin_save, TRUE);
+			    --no_u_sync;
+			}
 
 			/* May need to update the screen again when there are
 			 * autocommands involved. */
diff --git a/src/version.c b/src/version.c
index 775b027f15..61e0bf0e51 100644
--- a/src/version.c
+++ b/src/version.c
@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    901,
 /**/
     900,
 /**/