[bug#42735] [PATCH] pre-inst-env: don't use GUIX_PACKAGE_PATH

[Mathieu Othacehe]

Hello Denis,

> ./pre-inst-env is supposed to use only the packages definitions that are in
> the guix source tree and not the host packages.
>
> However if GUIX_PACKAGE_PATH is set, it will use host packages as well.

Let say you have a custom my-hello package inheriting from hello, and
you want to build it on top of a recent Guix checkout, then you probably
want GUIX_PACKAGE_PATH to cooperate with pre-inst-env.

Same goes if you have a manifest mixing Guix packages and custom
packages accessed by GUIX_PACKAGE_PATH, and you want to test your
manifest on top of a Guix checkout using pre-inst-env.

Thanks,

Mathieu