bug#54350: Profile collisions in "guix shell"

[Konrad Hinsen <konrad.hinsen@fastmail.net>]

Hi everyone,

I ran into this issue when I was trying to turn a much-used shell
environment into a profile for persisting the binaries in the store.
I had been using it for several months, believing it to be OK.
Fortunately it was easy to fix.

Background: as part of a reproducible computation workflow (see my talk
at the ten-year meeting,
https://10years.guix.gnu.org/program/#guix-as-a-tool-for-computational-science),
I run everything that is part of a research project in containers,
meaning "guix shell -C". Since I rely on Python 2 software, I end up
using package transformations frequently to get old software to work. As
it turns out now, package transformations are also an excellent way to
create profile collisions: three out of five of my commonly used
containers have collisions, which I wasn't aware of until a few days
ago.

From that perspective, the current behavior of "guix shell" is... let's
say "suboptimal".

I do understand the motivation, as explained in this thread, but I don't
quite understand (1) why profile collisions are so frequent in
development environments and (2) why ignoring them in that use case
doesn't cause any trouble.

When I run "guix shell -D inkscape", I expect to have, as much as
possible, the same environment as the one the daemon uses when build
inkscape. Does the daemon also switch off collision detection?

Cheers,
  Konrad.