I did the following:

--8<---------------cut here---------------start------------->8---
guix environment guix
./bootstrap
./configure --localstatedir="/var"
./pre-inst-env guile
--8<---------------cut here---------------end--------------->8---

And inside Guile REPL:

--8<---------------cut here---------------start------------->8---
,use (guix build syscalls)
(utmpx-entries)
--8<---------------cut here---------------end--------------->8---

And I get what is attached in "utmp-1.txt".

The same result is observed when I append `--ad-hoc guile' to `guix
environment guix' (I attempted a `diff' between the results of two
sequence of commands and it didn't report anything).