Hi!

Rewriting the bootstrap on the wip-bootstrap branch I found additional
inputs in packages that use `package-with-explicit-inputs', such as
diffutils-boot0.

I would expect diffutils-boot0 to list just one extra input in addition
to gnu-make-boot0; namely the package gnu-make-boot0; however it has
many more.

To reproduce this I created a test file with two simple packages
gnu-make-explicit-inputs, gnu-make-no-implicit-inputs.

Put the attached file in gnu/packages and producing a graph for both
test packages

--8<---------------cut here---------------start------------->8---
11:56:03 janneke@dundal:~/src/guix-master 
$ ./pre-inst-env guix graph --type=bag -e '(begin (use-modules (guix packages)) (@@ (gnu packages pawei) gnu-make-no-implicit-inputs))' | wc -l
14
11:56:22 janneke@dundal:~/src/guix-master 
$ ./pre-inst-env guix graph --type=bag -e '(begin (use-modules (guix packages)) (@@ (gnu packages pawei) gnu-make-explicit-inputs))' | wc -l
79
--8<---------------cut here---------------end--------------->8---

Should `package-with-explicit-inputs' behave like I think it does, i.e.,
should both test packages list the same dependencies, or am I missing
something?