Hi Ludo,

> This works well for me:

> $ guix shell --expose=/gnu/store --expose=/var/guix/daemon-socket -C guix -- guix shell -C coreutils

That works fine for me as well. It stops working when I add -N to the
first container:

$ guix shell --expose=/gnu/store --expose=/var/guix/daemon-socket -C -N guix -- guix shell -C coreutils
guix shell: error: mount: mount "none" on "/tmp/guix-directory.wxW0wg/sys": Operation not permitted

It works again when I add -N to the second container as well:

$ guix shell --expose=/gnu/store --expose=/var/guix/daemon-socket -C -N guix -- guix shell -C -N coreutils
[env]$ ls /gnu/store
094bbaq6glba86h1d4cj16xhdi6fk2jl-gcc-10.3.0-lib
1z962p14zfpx3c3k38bkn8ip2klj75m7-emacs-subdirs
5h2w4qi9hk1qzzgi1w83220ydslinr4s-glibc-2.33
720rj90bch716isd8z7lcwrnvz28ap4y-bash-static-5.1.8
8fpk2cja3f07xls48jfnpgrzrljpqivr-coreutils-8.32
9rrnm5hdjw7cy96a2a9rfgh6y08wsbmf-ncurses-6.2.20210619
a38k2v29l6l0iz6pmlk4dmzwdbvl10lq-acl-2.3.1
a7ggx0af69gv4k5mr1k617p4vy9kgx2v-libcap-2.62
d99ykvj3axzzidygsmdmzxah4lvxd6hw-bash-5.1.8
fwbiihd2sbhai63y1pvvdh0f2bakfzrf-gmp-6.2.1
jkjs0inmzhj4vsvclbf08nmh0shm7lrf-attr-2.5.1
v06kj3rm9fq6xz5x3c9q67fqhxqgvgiy-profile
wcwls45278gzpjvwlvrrs1y7h30g44xh-readline-8.1.1
xx946lncjfqic6dg1pgaisg09jy8fqka-info-dir

> It’s weird that it’s not deterministic.

It's deterministic, but it seems to depend on the packages that are in
each container.

> Could you prepend your command with:
>
>   strace -f -o /tmp/log -s 100
>
> and share /tmp/log?

Attached.

> What does ‘uname -rv’ report?

$ uname -rv
5.14.0-1052-oem #59-Ubuntu SMP Fri Sep 9 09:37:59 UTC 2022

> Is this on a foreign distro?

Yes, Ubuntu 20.04.

Cheers,
  Konrad