Subject: make check fails for Guix 0.13.0

From: <[email-masked]>
Date: Tue, 23 May 2017 15:21:33 +0200 (CEST)

I can confirm this error on my end, using UEFI aswell and having
a partition mounted in /mnt/boot/efi formated with fat 32 (going by Gentoo Handbook).