M-x guix-system-generations vs. UUIDs

[ludo@gnu.org (Ludovic Courtès)]

Howdy Alex,

I just noticed that ‘M-x guix-system-generations’ followed by ‘i’
doesn’t correctly handle UUID objects in the ‘root-device’ or
‘store-device’ fields.  Here’s the backtrace:

--8<---------------cut here---------------start------------->8---
Debugger entered--Lisp error: (invalid-read-syntax "#")
  read("(((id . 42) (number . 42) (prev-number . 41) (current . t) (file-name . \"/var/guix/profiles/system-42-link\") (time . 1507101359) (label . \"GNU with Linux-Libre 4.13.4 (beta)\") (root-device . #<<uuid> type: dce bv: #vu8(210 86 …)>) (store-device . #<<uuid> type: dce bv: #vu8(210 86 …)>) (store-mount-point . \"/\") (bootloader . grub-efi) (kernel . \"/gnu/store/sm1xr358drdflv6fz3ii6g0rcmk5fsv7-linux-libre-4.13.4/bzImage\")))")
  guix-geiser-eval-read("(system-generation-sexps \"/var/guix/profiles/system\" 'id '(42) '(kernel number id label prev-number current number-of-packages file-name time bootloader root-device store-device store-mount-point kernel-arguments kernel-config shepherd-config))" #<buffer *Guix Internal REPL*>)
  guix-eval-read("(system-generation-sexps \"/var/guix/profiles/system\" 'id '(42) '(kernel number id label prev-number current number-of-packages file-name time bootloader root-device store-device store-mount-point kernel-arguments kernel-config shepherd-config))")
  guix-generation-get-entries(system-generation-sexps "/var/guix/profiles/system" id (42) (kernel number id label prev-number current number-of-packages file-name time bootloader root-device store-device store-mount-point kernel-arguments kernel-config shepherd-config))
  guix-system-generation-get-entries("/var/guix/profiles/system" id (42) (number id label prev-number current number-of-packages file-name time bootloader root-device store-device store-mount-point kernel-arguments kernel-config shepherd-config))
  guix-system-generation-info-get-entries("/var/guix/profiles/system" id 42)
  apply(guix-system-generation-info-get-entries ("/var/guix/profiles/system" id 42))
  bui-get-entries(guix-system-generation info ("/var/guix/profiles/system" id 42))
  bui-get-display-entries(guix-system-generation info ("/var/guix/profiles/system" id 42) add)
  guix-ui-list-describe(42)
  apply(guix-ui-list-describe 42)
  bui-list-describe(general)
  funcall-interactively(bui-list-describe general)
  call-interactively(bui-list-describe nil nil)
  command-execute(bui-list-describe)
--8<---------------cut here---------------end--------------->8---

I wonder if this was already the case before the introduction of <uuid>
objects in commit 9b336338cdc0e46a3bf7a2913c2f61cd2410c4d6, when UUIDs
were referred to as bytevectors.

Thoughts?

Ludo’.