bug#36785: Impossible to pull on foreign distro

[Ludovic Courtès]

Hi Julien,

Julien Lepiller <address@hidden> skribis:

> I gave a small tutorial to someone today, where we installed guix on top of a 
> foreign distro. We used the script and everything went smoothly, and after 
> finding out that we were going to build php (we were trying to define a VM 
> that would serve one of their services), we tried to run guix pull:
>
> sudo guix pull —commit=…
>
> However the command failed immediately with:
>
> Migrating profile generations to '/var/guix/profiles/per-user/root'...
> Guix pull: error: symlink: File exists: 
> "/var/guix/profiles/per-user/root/current-guix"
>
> Indeed, the file exists and everything looks good. Why does guix try to 
> migrate a profile that's already good?
>
> I was able to work around that situation, but it's not great for our users.

I’m guessing the machine had remnants of a previous Guix installation,
no?  See:

  ;; In 0.15.0+ we'd create ~/.config/guix/current-[0-9]*-link symlinks.  Move
  ;; them to %PROFILE-DIRECTORY.
  (unless (string=? %profile-directory
                    (dirname (canonicalize-profile %user-profile-directory)))
    (migrate-generations %user-profile-directory %profile-directory))

Ludo’.