bug#55857: Odd Shepherd message on 'guix system reconfigure': (map (# ?) ?)

[Maxim Cournoyer]

Hello Guix,

The following message is shown when reconfiguring Guix System:

--8<---------------cut here---------------start------------->8---
shepherd: Evaluating user expression (and (defined? (quote transient?)) (map (# 
?) ?)).
--8<---------------cut here---------------end--------------->8---

It doesn't seem intended for end users to see; at least I have no clue
what it's supposed to tell me :-).

Thanks,

Maxim