To reproduce:

$ guix build ruby-stackprof@0.2.17 --system=???
# if it was substituted
$ guix build ruby-stackprof@0.2.17 --system=??? --no-grafts --check

where I don't know what the value of ??? is (maybe armhf-linux?).
Maybe it fails on other architectures too, but I cannot reproduce
it on i686-linux.

Apparently this can cause "guix pull" to fail, see
<https://issues.guix.gnu.org/54651>.

Greetings,
Maxime.