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)
diff --git a/src/version.c b/src/version.c
index 775b027..61e0bf0 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    901,
+/**/
     900,
 /**/
     899,