bug#39341: Installer using 100% of a CPU core

[Maxim Cournoyer]

While using the Guix 1.0.1 installer, I noticed that it was constantly
maxing one of the cores on the machine.

The guilty process is:

--8<---------------cut here---------------start------------->8---
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root       377 99.8  0.3  37268 10328 ?        Rs   08:20 377:09 
/gnu/store/8asv37pjsq3n4b4hgz9ys840f9j531hk-kmscon-0.0.0-1.01dd0a2/libexec/kmscon/kmscon
 --login --vt tty1 --no-switchvt --login -- 
/gnu/store/cb92798ps1xpla3ai14ik81vkl7jbw97-installer -p
--8<---------------cut here---------------end--------------->8---