bug#30569: Packages count as installed twice

[ludo@gnu.org (Ludovic Courtès)]

Andreas Enge <andreas@enge.fr> skribis:

> On Wed, Feb 21, 2018 at 11:14:21PM +0100, Ricardo Wurmus wrote:
>> Even so, you’ll have a file called “manifest” in the profile directory.
>> This is unrelated to whether you used a manifest to create the profile
>> or not.
>
> I see! Yes, it appeared twice.

Looking more closely, it’s actually possible even now to create a
profile with the exact same entry twice:

--8<---------------cut here---------------start------------->8---
$ guix package -p foo -i gnutls gnutls
La jenaj pakoj estos instalataj:
    gnutls	3.5.13	/gnu/store/g09is0bw144d8zrd059fiarqmjq7vr8a-gnutls-3.5.13
   gnutls	3.5.13	/gnu/store/g09is0bw144d8zrd059fiarqmjq7vr8a-gnutls-3.5.13

substitute: updating list of substitutes from 'https://berlin.guixsd.org'... 100.0%
substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
La jenaj derivoj estos konstruataj:
   /gnu/store/viykf0jcxc9c51yl0p1023b75khad7jn-profile.drv
   /gnu/store/yi996sf93p8n15ijf27hcck1b6prywrl-info-dir.drv
   /gnu/store/ki7jrd29isi0l1zk93vrqd1p4by08nw7-fonts-dir.drv
   /gnu/store/0xkp49578vpjc7q96kyg052v4jhx439m-ca-certificate-bundle.drv
   /gnu/store/yxbrnjbxjcdx6nvs8l0wm8236mvx14l7-manual-database.drv
Creating manual page database...
144 entries processed in 0.1 s
pakoj 2 en profilo
La jenaj medi-variablaj difinoj povos esti necesaj:
   export PATH="foo/bin${PATH:+:}$PATH"
--8<---------------cut here---------------end--------------->8---

Weird, but no big deal since they are really the same entry.

(What’s *not* permitted is installing several “gnutls” packages having a
different store file name.  See ‘check-for-collisions’ in (guix
profiles).)

What should we do?  Status quo?  Throwing a ‘delete-duplicates’ call?
Let’s have a poll!  ;-)

Ludo’.