Subject: bug#55639: time-machine back in 2020: weird error

From: zimoun <[email-masked]>
Date: Wed, 25 May 2022 19:13:12 +0200

Hi,

>From 9d795fb, I get on machine A,

--8<---------------cut here---------------start------------->8---
$ guix time-machine --commit=a7b20226b2 -- build hello
[...]
Backtrace:
           1 (primitive-load "/home/simon/.cache/guix/inferiors/wulv?")
In guix/ui.scm:
  1936:12  0 (run-guix-command _ . _)

guix/ui.scm:1936:12: In procedure run-guix-command:
Throw to key `match-error' with args `("match" "no matching pattern" #<derivation /gnu/store/c6hgmfq0i4zgryqyl0ab1ms51fnrkmdv-bootstrap-binaries-0.drv => /gnu/store/5bdaayvl6cs8nrdivskz4dbrsy2m009c-bootstrap-binaries-0 7fcda0633a50>)'.
--8<---------------cut here---------------end--------------->8---

where it reads:

--8<---------------cut here---------------start------------->8---
$ guix gc --list-live | grep c6hgmfq0i4zgryqyl0ab1ms51fnrkmdv
finding garbage collector roots...
determining live/dead paths...
/gnu/store/c6hgmfq0i4zgryqyl0ab1ms51fnrkmdv-bootstrap-binaries-0.drv

$ guix gc --list-dead | grep 5bdaayvl6cs8nrdivskz4dbrsy2m009c
finding garbage collector roots...
determining live/dead paths...
/gnu/store/5bdaayvl6cs8nrdivskz4dbrsy2m009c-bootstrap-binaries-0

$ guix build /gnu/store/c6hgmfq0i4zgryqyl0ab1ms51fnrkmdv-bootstrap-binaries-0.drv
/gnu/store/5bdaayvl6cs8nrdivskz4dbrsy2m009c-bootstrap-binaries-0
--8<---------------cut here---------------end--------------->8---

Last, on machine B, the time-machine just works.  Maybe it is related to
NVMe and something like [1].

Well, I still do not understand why the time-machine raises an error
when the store have the necessary item.  Any idea?

1: <https://issues.guix.gnu.org/41264>

Cheers,
simon