bug#66662: References to ungrafted glibc retained

[Ludovic Courtès]

As discussed while reviewing the now-applied glibc replacement at
<https://issues.guix.gnu.org/66348>, I stumbled upon a case where a
package still refers to a ungrafted glibc in addition to the grafted
one:

--8<---------------cut here---------------start------------->8---
$ guix gc -R $(guix build libreoffice) | grep glibc-2.35
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
/gnu/store/ln6hxqjvz6m9gdd9s97pivlqck7hzs99-glibc-2.35
$ guix build -e '(@@ (gnu packages commencement) glibc-final)'
/gnu/store/gd0x2az3a0sgj5aa9fbv201g7wwfj5m7-glibc-2.35-debug
/gnu/store/ln6hxqjvz6m9gdd9s97pivlqck7hzs99-glibc-2.35
/gnu/store/i2g0is6wjq3ccs6m1l6w9mhf44k4042h-glibc-2.35-static
$ guix build -e '(@@ (gnu packages commencement) glibc-final)' --no-grafts
/gnu/store/0lzva77yj6hddmhasia65krknyi8kxsg-glibc-2.35-debug
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
/gnu/store/l0yryi5jsa1grnvw01c9nkz9c81cv224-glibc-2.35-static
$ guix describe
Generation 277  Oct 16 2023 23:15:43    (current)
  guix b437896
    repository URL: https://git.savannah.gnu.org/git/guix.git
    branch: master
    commit: b437896e87a51cc610388d4c462893652dd773e6
--8<---------------cut here---------------end--------------->8---

The path to the ungrafted libc goes like this:

--8<---------------cut here---------------start------------->8---
$ guix graph --path -t references $(guix build libreoffice) 
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
/gnu/store/n8y9jk8wnvxxg54g19ds0jf5agiv5vs2-libreoffice-7.5.4.2
/gnu/store/y392yldk4pbk4z5q587bz5n61hzbcf4g-mariadb-10.10.2-dev
/gnu/store/cilkyfnc5fxmpviyypci3d2881ik3nih-mariadb-10.10.2-lib
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
--8<---------------cut here---------------end--------------->8---

Similar problem with GIMP:

--8<---------------cut here---------------start------------->8---
$ guix gc -R $(guix build gimp) | grep glibc-2.35
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
/gnu/store/ln6hxqjvz6m9gdd9s97pivlqck7hzs99-glibc-2.35
$ guix graph --path -t references $(guix build gimp |grep -v doc) 
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
/gnu/store/fw40cg57p0ycggrf8qvhl116257c5vv7-gimp-2.10.32
/gnu/store/mhfdl59lwhv4nh5kd4pnrh8jjls6976w-exiv2-0.27.5
/gnu/store/47xjz7g247yrnfxbkpr0hi81cqkrlvdn-gcc-11.3.0
/gnu/store/930nwsiysdvy2x5zv1sf6v7ym75z8ayk-gcc-11.3.0-lib
/gnu/store/gsjczqir1wbz8p770zndrpw4rnppmxi3-glibc-2.35
--8<---------------cut here---------------end--------------->8---

Ludo’.