From: Tim Niemeyer <tim@tn-x.org>
Date: Sat, 8 Jul 2017 10:46:59 +0200
Subject: Disable OpenWrt config migration mechanisms

This disables all OpenWrt config migration mechanisms except for
files listed in /etc/sysupgrade.conf

diff --git a/package/base-files/files/sbin/sysupgrade b/package/base-files/files/sbin/sysupgrade
index 7e0a00e13b8ee4be7163936fd01a7beff0ce5c99..97f50dc83088e29fba651741fff28c70f7585b3f 100755
--- a/package/base-files/files/sbin/sysupgrade
+++ b/package/base-files/files/sbin/sysupgrade
@@ -135,14 +135,14 @@ list_static_conffiles() {
 	local filter=$1
 
 	find $(sed -ne '/^[[:space:]]*$/d; /^#/d; p' \
-		/etc/sysupgrade.conf /lib/upgrade/keep.d/* 2>/dev/null) \
+		/etc/sysupgrade.conf 2>/dev/null) \
 		\( -type f -o -type l \) $filter 2>/dev/null
 }
 
 add_conffiles() {
 	local file="$1"
 
-	( list_static_conffiles "$find_filter"; list_changed_conffiles ) |
+	( list_static_conffiles "$find_filter" ) |
 		sort -u > "$file"
 	return 0
 }