GNU bug Tracking System writes:

Hi Tobias,

As reported by oscar123123 on irc, this broke guix pull

To reproduce:

--8<---------------cut here---------------start------------->8---
guix pull --commit=a23091880d4dc6115acbfa3b7ef09d731fc5abb0
--8<---------------cut here---------------end--------------->8---

Tobias reverted the commit (thanks!).

I found this test to also show the failure.

--8<---------------cut here---------------start------------->8---
make check TESTS=tests/guix-system.sh
--8<---------------cut here---------------end--------------->8---

It turns out that this test creates a grub bootsloader with #f for
config.

Attached is a new version of the patch, that is robust against this;
this being the difference:

--8<---------------cut here---------------start------------->8---
diff --git a/gnu/bootloader/grub.scm b/gnu/bootloader/grub.scm
index 55e6344285..b99f5fa4f4 100644
--- a/gnu/bootloader/grub.scm
+++ b/gnu/bootloader/grub.scm
@@ -152,10 +152,16 @@ system string---e.g., \"x86_64-linux\"."
     ;; most other modern architectures have no other mode and therefore don't
     ;; need to be switched.
     (if (string-match "^(x86_64|i[3-6]86)-" system)
-        (string-append "
-  set gfxmode=" (string-join
-                 (grub-gfxmode (bootloader-configuration-theme config))
-                 ";") "
+        (string-append
+         "
+"
+         (let ((gfxmode (and=>
+                         (and=> config bootloader-configuration-theme)
+                         grub-gfxmode)))
+           (if gfxmode
+               (string-append "set gfxmode=" (string-join gfxmode ";"))
+               "# Leave 'gfxmode' to 'auto'."))
+         "
   insmod video_bochs
   insmod video_cirrus
   insmod gfxterm
--8<---------------cut here---------------end--------------->8---

This fixes make check and I also tested that

--8<---------------cut here---------------start------------->8---
guix pull --url=$PWD
--8<---------------cut here---------------end--------------->8---

now succeeds.

Greetings,
janneke