Hi again Leo!

That doesn't say much, because `guix environment` provides little
> isolation.  You might try with pure environments, but the better way of
> replicating the build environment is using `-K`.
>

Ran in a `guix environment --pure --container` and it still built
successfully.


> I have yet to look at your package definition (pardon me), but do you
> notice anything strange between the Makefiles you generate on your own
> vs. the Makefiles you generate in `guix build`?
>

Thanks for the idea. Made me realise that I could run the build steps on my
own in the /tmp/ folders `guix build` generates with `--keep-failed`. And
in doing so I got it to build even there. Figured that it then has to be
some difference in the build steps and have now figured out that it is the
flag "-DCMAKE_BUILD_TYPE=RelWithDebInfo" that is causing the issue. If I
changed that to `Release` instead of `RelWithDebInfo` then the package
builds successfully. And it also has plugins now!

I will return with a revised version later. First I will try to package
libpsd, an optional dependency of Nomacs.