bug#41607: Deleted store items are not actually deleted

[Leo Famulari]

>From the discussion "Guix Docker image inflation" [0] on help-guix:

On Fri, May 29, 2020 at 02:29:53PM -0400, Stephen Scheck wrote:
> # Now try to delete it...
> root@localhost /gnu/store# guix gc --delete
> /gnu/store/x7ns2xcp8lfg24zq7gr3y8ffczn1nsxp-guix-d79c917f2-modules
> finding garbage collector roots...
> [0 MiB] deleting
> '/gnu/store/x7ns2xcp8lfg24zq7gr3y8ffczn1nsxp-guix-d79c917f2-modules'
> deleting `/gnu/store/trash'
> deleting unused links...
> note: currently hard linking saves 1181.36 MiB
> 
> # Still there...
> root@localhost /gnu/store# du -hs
> /gnu/store/x7ns2xcp8lfg24zq7gr3y8ffczn1nsxp-guix-d79c917f2-modules
> 210M /gnu/store/x7ns2xcp8lfg24zq7gr3y8ffczn1nsxp-guix-d79c917f2-modules

Okay, something is definitely not right.

[0] https://lists.gnu.org/archive/html/help-guix/2020-05/msg00235.html