Unfortunate statefulness of Guix Install image

[Vladilen Kozin]

Hello Guix.

This may or may not be a "bug", but thought I'd report something I run
into. I found that GUI install never worked for me but booting off
Guix Install USB and then following
https://guix.gnu.org/manual/en/html_node/Manual-Installation.html
worked perfectly fine. Except, when you try to do the manual install
off the same USB ... twice. That is, having installed a system once
off that USB, you then try to install another and your `guix system
init path/to/config.scm /mnt` would almost immediately fail with error
saying that some expected derivation have not been found in the store.

My best guess from what I've read in the manual is this. Store is not
the only place where derivations appear. /var/guix/db stores metadata
about said derivations. So the first time you do `herd start cow-store
/mnt` trick it'll create the store there but will populate the db on
that USB drive. Next time you try to install from that same USB on a
different machine it'll have its db reference derivations that are no
longer available. I worked around this by stupidly `mv /var/guix/db
/var/guix/db.old` and `guix system init` went without trouble.

I guess my complaint is that at least the manual way (maybe GUI
install, too) is completely stateful and turns that USB stick into
"consumable good" unless you know about the database.

Sorry, dunno enough about Guix, so maybe I've been doing something wrong.
-- 
Best regards
Vlad Kozin