We have a problem!  Depending on whether grafts are enabled, we end up
building one of two different derivations for ‘guix’ (“real”
derivations; none of them is a mere grafting derivation):

--8<---------------cut here---------------start------------->8---
$ guix describe
Generation 241  Jan 16 2023 00:26:44    (current)
  guix 5c92197
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: 5c921977179489caef4a9e54ada6696fc86d2f0b
$ guix build guix -n
The following derivation would be built:
  /gnu/store/hfaffzsjia7x1rbwaryyygh01bskxvvx-guix-1.4.0-1.9fe5b49.drv
$ guix build guix -n --no-grafts
/gnu/store/zasc3k9cnk3l1kvi03a4wml33awg21gf-guix-1.4.0-1.9fe5b49
$ guix build guix -n --no-grafts -d
/gnu/store/lczdc4jl1yl7cf4mrzqw2b9wiwmc5pwb-guix-1.4.0-1.9fe5b49.drv
--8<---------------cut here---------------end--------------->8---

The difference between those two .drv is guile-gnutls-3.7.11.drv, which
themselves differ in their gnulib-2022-12-06-1.440b528.drv.  At the
bottom, the difference is: