Boot of guixSD was interrupted by "In execvp of fsck.ext4: No such file
or directory" followed by a Bourne-like REPL. Entering ",q" allows boot
to continue normally.

This occurred while booting generation 7 (see below). Generation 6
booted normally.

Attached is my operating-system configuration.

bash-4.4$ uname -a
Linux guix 4.8.12-gnu #1 SMP 1 x86_64 GNU/Linux
bash-4.4$ which ext4.fsck
which: no ext4.fsck in
(/home/alex/.guix-profile/bin:/run/setuid-programs:/run/current-system/profile/bin:/run/current-system/profile/sbin)

Generations:
scheme@(guile-user)> (guix-command "system" "list-generations")
Generation 1	Sep 06 2016 22:48:27
  file name: /var/guix/profiles/system-1-link
  canonical file name: /gnu/store/m5c43nhr363j2gsf5js7ryrp50bbdhq8-system
  label: GNU with Linux-Libre 4.7 (beta)
  root device: guix
  kernel: /gnu/store/mbzkpw70jrck9z4hi032vdjff01w02aa-linux-libre-4.7/bzImage
Generation 2	Sep 10 2016 11:32:04
  file name: /var/guix/profiles/system-2-link
  canonical file name: /gnu/store/i2xm3k3vaxacv9pw78740419gn22dzdg-system
  label: GNU with Linux-Libre 4.7.2 (beta)
  root device: guix
  kernel: /gnu/store/1w33nqlw4il84i4xr3pif45insmz82ln-linux-libre-4.7.2/bzImage
Generation 3	Sep 10 2016 11:32:04
  file name: /var/guix/profiles/system-3-link
  canonical file name: /gnu/store/i2xm3k3vaxacv9pw78740419gn22dzdg-system
  label: GNU with Linux-Libre 4.7.2 (beta)
  root device: guix
  kernel: /gnu/store/1w33nqlw4il84i4xr3pif45insmz82ln-linux-libre-4.7.2/bzImage
Generation 4	Sep 10 2016 11:32:04
  file name: /var/guix/profiles/system-4-link
  canonical file name: /gnu/store/i2xm3k3vaxacv9pw78740419gn22dzdg-system
  label: GNU with Linux-Libre 4.7.2 (beta)
  root device: guix
  kernel: /gnu/store/1w33nqlw4il84i4xr3pif45insmz82ln-linux-libre-4.7.2/bzImage
Generation 5	Sep 11 2016 15:17:57
  file name: /var/guix/profiles/system-5-link
  canonical file name: /gnu/store/735jsch2rki7vq6pxp5174hnjzc21v2q-system
  label: GNU with Linux-Libre 4.7.2 (beta)
  root device: guix
  kernel: /gnu/store/1w33nqlw4il84i4xr3pif45insmz82ln-linux-libre-4.7.2/bzImage
Generation 6	Sep 16 2016 23:06:18
  file name: /var/guix/profiles/system-6-link
  canonical file name: /gnu/store/6j3kpanxm63ws3nhgp75vgpf30fbaxwj-system
  label: GNU with Linux-Libre 4.7.2 (beta)
  root device: guix
  kernel: /gnu/store/1w33nqlw4il84i4xr3pif45insmz82ln-linux-libre-4.7.2/bzImage
Generation 7	Dec 04 2016 19:58:23	(current)
  file name: /var/guix/profiles/system-7-link
  canonical file name: /gnu/store/0l1ia1vbja1pmlvl5v3w2n0q7w0b5im2-system
  label: GNU with Linux-Libre 4.8.12 (beta)
  root device: guix
  kernel: /gnu/store/90nmdrl491nyhsy7ar1zczvz5wgqlymh-linux-libre-4.8.12/bzImage