bug#72061: Discrepancy when running ‘guix pull’ from different machines

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

Hi everyone,

Jumping in with a possibly related problem reported by a participant of
the Reproducible Research MOOC.

He gets an error when running an example from one of our exercises:

   guix time-machine --channels=channels.scm -- shell --container --network --manifest=manifest.scm -- jupyter lab
   guix-science/build-system/node.scm:119:2: error: #{ %make-build-system-procedure/abi-check}#: unbound variable
   hint: Did you forget a `use-modules' form?

It's this error message that led me to this thread. He gets the same
error message when running some of our other examples.

I asked for his channels and did a "guix pull" on my machine with the
exact same ones. But there's no problem for me, everything works fine.

Inspired by the reference to "old guix-daemon", I asked him to update
his daemon. After that, he still gets the error message but the
time-machined "shell" command is run nevertheless - and produces another
error that it doesn't produce on my machine.

Are there any diagnostics we can do to explore this issue?

Cheers,
  Konrad