Hi,

I've been looking into managing my Emacs packages with Guix. I found that the `emacs-guix` package doesn't seem to show up in the `package-activated-list`, even though its dependencies do, which seems like a bug. Here's an illustration:

```
philip@avalon:/tmp/emacs-bug$ guix describe --format=channels
(list (channel
        (name 'guix)
        (url "https://git.savannah.gnu.org/git/guix.git")
        (branch "master")
        (commit
          "e069de452a2c923868f5137421b4b6349c38d754")
        (introduction
          (make-channel-introduction
            "9edb3f66fd807b096b48283debdcddccfea34bad"
            (openpgp-fingerprint
              "BBB0 2DDF 2CEA F6A8 0D1D  E643 A2A0 6DF2 A33A 54FA")))))
philip@avalon:/tmp/emacs-bug$ cat demo.el 
(require 'package)
(package-initialize)                                                     
(print package-activated-list)
philip@avalon:/tmp/emacs-bug$ guix shell --pure --container emacs emacs-guix -- emacs --script demo.el
Loading /gnu/store/7vpfhr5fzvyvnh62lj17b97q7vr0svjj-emacs-guix-0.5.2-5.c9aef52/share/emacs/site-lisp/guix-0.5.2-5.c9aef52/guix-autoloads.el (source)...
Loading /gnu/store/4hnp17pjbvi3xirk9ygxzv5hb24c9ghk-emacs-bui-1.2.1/share/emacs/site-lisp/bui-1.2.1/bui-autoloads...
Loading /gnu/store/gx62xcfnn7dw1ib88gzbvgbz255vrd9i-emacs-dash-2.19.1/share/emacs/site-lisp/dash-2.19.1/dash-autoloads...
Loading /gnu/store/aqbcw5fjmsr4lndhpgs4bzgd58a16rkw-emacs-edit-indirect-0.1.8/share/emacs/site-lisp/edit-indirect-0.1.8/edit-indirect-autoloads...
Loading /gnu/store/sic558dq3rlcx6d0f1h7pq6cq1mkliaz-emacs-geiser-0.23.2/share/emacs/site-lisp/geiser-0.23.2/geiser-autoloads...
Loading /gnu/store/qc3b61ygmgpnhssy4yvk4a66xcd81kss-emacs-project-0.8.1/share/emacs/site-lisp/project-0.8.1/project-autoloads...
Loading /gnu/store/6al6nhnkxkgznh7fla8rsyis8cxywz6l-emacs-xref-1.4.1/share/emacs/site-lisp/xref-1.4.1/xref-autoloads...
Loading /gnu/store/g2b2bagb3p1vw57kxgry7pnh32grl4d0-emacs-transient-0.3.7/share/emacs/site-lisp/transient-0.3.7/transient-autoloads...
Loading /gnu/store/dacdgzvhn1n4j8dcac6d67vnc9fnlmym-emacs-geiser-guile-0.23.2/share/emacs/site-lisp/geiser-guile-0.23.2/geiser-guile-autoloads...
Loading /gnu/store/l7qm8v9pnpadllxyr6g348a4knfj4x42-emacs-magit-popup-2.13.3/share/emacs/site-lisp/magit-popup-2.13.3/magit-popup-autoloads...

(bui edit-indirect xref geiser-guile geiser magit-popup dash)
```