Hey,

> This is fixed by 6abdcef4a68e98f538ab69fde096adc5f5ca4ff4; the log
> contains extra details.

Thanks for fixing it! Turns out we still have an issue on all four
installer tests.

The error messages look like:

--8<---------------cut here---------------start------------->8---
Sep 22 09:49:19 localhost installer[252]: running command ("guix" "system" "init" "--fallback" "--no-grafts" "--no-substitutes" "/mnt/etc/config.scm" "/mnt") 

Sep 22 09:49:21 localhost installer[252]: guix system: error: read error while loading '/mnt/etc/config.scm': /mnt/etc/config.scm:63:51: unexpected ")" 
--8<---------------cut here---------------end--------------->8---

Having a look at the configuration file (attached), it seems that the
problem comes from the edit-configuration-file function. As the
rewritten configuration is shorter than the initial because the comments
are stripped by the pretty-print function, we have some leftovers from
the initial config.

I do not really understand why because call-with-output-file is supposed
to use the O_TRUNC flag and remove the existing content of the
configuration file. Plus, calling edit-configuration-file from a guix
repl does the right thing.

Anyways, I pushed fe4663ae2476cb527d4f1f49ff8fa077d43f7251 which fixes
the issue by removing the file before rewriting it.

Mathieu