diff -urNp grub-2.02-rc1.orig/util/grub-mkconfig.in grub-2.02-rc1/util/grub-mkconfig.in
--- grub-2.02-rc1.orig/util/grub-mkconfig.in	2017-02-08 15:05:01.428318167 +0000
+++ grub-2.02-rc1/util/grub-mkconfig.in	2017-02-08 15:05:13.547318031 +0000
@@ -1,5 +1,6 @@
 #! /bin/sh
 set -e
+set -o posix
 
 # Generate grub.cfg by inspecting /boot contents.
 # Copyright (C) 2006,2007,2008,2009,2010 Free Software Foundation, Inc.