bug#35582: Installer: Graphical installation failed because of truncated UUID

[sirgazil]

Hi,

I installed the GNU system with the Guix 1.0 ISO installer 
(https://ftp.gnu.org/gnu/guix/guix-system-install-1.0.0.x86_64-linux.iso.xz). 
My intention was to complete the installation using the graphical installer, 
but my attempts failed with an error that pointed to the line in the 
"config.scm" where the EFI partition UUID was defined (I don't remember the 
exact error, but I think I mentioned it on #guix).

In my case, the installer generated this:

```
(file-system
  (mount-point "/boot/efi")
  (device (uuid "A0CA-50E" 'fat32))
  (type "vfat"))
```

However, running "blkid" would display the correct UUID as `A0CA-050E`. So, for 
some reason, the zero before 5 was omitted in the configuration generated by 
the installer. The issue happened every time I restarted the machine to try the 
installation again (around 4 times).

Because of this I couldn't finish the installation normally, and had to modify 
the UUID in the generated "config.scm" by hand (adding the missing 0) and, also 
manually, run the rest of the necessary commands for installing the system:

    herd start cow-store /mnt
    guix system init /mnt/etc/config.scm /mnt

Completing the process manually also required to assign passwords manually for 
root and the user I had created during the graphical steps. The passwords 
indicated for them during the graphical steps were not applied to the installed 
system.


---
https://sirgazil.bitbucket.io/