bug#23132: Grafted system retains references to original store items

[Mark H Weaver]

While testing my preliminary work on grafting improvements, I discovered
that my current system is retaining references to the original flawed
openssl-1.0.2f.  One path of references goes like this:

   /gnu/store/pnbljdp1hpsvnbgqfl8bws7lpj7pm8cb-system
-> /gnu/store/bzdhckvz4sms136fw64pvyhajawdb8ri-profile
-> /gnu/store/dhrgkq1zfkkc5rnz51qlshakapsa2sgm-gnome-session-3.18.1.2
-> /gnu/store/55pqh3wl085d4h033n41b7x0fg9djd1k-glib-2.46.1-bin
-> /gnu/store/kkn66257xrrjhyhq332bndhjpz4d9x76-python-wrapper-3.4.3
-> /gnu/store/qrg3jza3p5281p255cx0lsqk8snbb6pq-python-3.4.3
-> /gnu/store/dgyc74zakg110dxj67z3mj9g1vk8l4xp-openssl-1.0.2f

The gnome-session store item above was created by a grafting derivation,
and all of the ones that follow (starting with glib-2.46.1-bin) are
ungrafted derivations.  The grafting derivation for gnome-session failed
to include a mapping for glib-2.46.1-bin.

  address@hidden:~$ guix build --log-file 
/gnu/store/dgyc74zakg110dxj67z3mj9g1vk8l4xp-openssl-1.0.2f
  https://hydra.gnu.org/log/dgyc74zakg110dxj67z3mj9g1vk8l4xp-openssl-1.0.2f

Here's the .drv file for the gnome-session store item above:

  address@hidden:~$ guix build --log-file 
/gnu/store/dhrgkq1zfkkc5rnz51qlshakapsa2sgm-gnome-session-3.18.1.2
  
/var/log/guix/drvs/b9/n4f67h7fi7l3g5brws2bxlpfx9qvgb-gnome-session-3.18.1.2.drv.bz2
  address@hidden:~$ bzcat 
/var/log/guix/drvs/b9/n4f67h7fi7l3g5brws2bxlpfx9qvgb-gnome-session-3.18.1.2.drv.bz2
  grafting '/gnu/store/2f25m1jyy7lvkjqgilza6bafbnv3k044-gnome-session-3.18.1.2' 
-> '/gnu/store/dhrgkq1zfkkc5rnz51qlshakapsa2sgm-gnome-session-3.18.1.2'...
  address@hidden:~$ cat 
/gnu/store/b9n4f67h7fi7l3g5brws2bxlpfx9qvgb-gnome-session-3.18.1.2.drv
  
Derive([("out","/gnu/store/dhrgkq1zfkkc5rnz51qlshakapsa2sgm-gnome-session-3.18.1.2","","")],[("/gnu/store/01fyw4i0n31jlc96bwfqc1k9nf0qpj9f-harfbuzz-1.0.6.drv",["out"]),("/gnu/store/023cbj8wlhqmzi0mcn4gkrbnya931a4v-gtk+-3.18.2.drv",["out"]),("/gnu/store/060zw0zzaavja4nmd6qwj1ik5gnx603l-cups-2.1.0.drv",["out"]),("/gnu/store/0h6js55xwls65g2v4dmg847xbdxcpk29-librsvg-2.40.13.drv",["out"]),("/gnu/store/0k7ghiwfsm2d35jn2hmlylkw1d61lyc4-cups-filters-1.4.0.drv",["out"]),("/gnu/store/0m8lfd0y29jhffm3k4r5260282z06r0r-module-import-compiled.drv",["out"]),("/gnu/store/1s6fgn054951yv4bqlpr0vdqb9qvmbkm-pango-1.38.1.drv",["out"]),("/gnu/store/3lchcs3vm4a6r4lknhc0dvc0v0fq1sas-gtk+-3.18.2.drv",["out"]),("/gnu/store/50bb3x82p2hzi9qhmj7qlnzxa3x6xsim-gnome-desktop-3.18.1.drv",["out"]),("/gnu/store/64kkvvcm0zks5cysg89gkcw6a69g5pp2-qpdf-5.1.3.drv",["out"]),("/gnu/store/72qn0wwgdkv8011c1cdrwjbwbqkw1kn1-graphite2-1.3.5.drv",["out"]),("/gnu/store/7l31sjng02yzrl05ki1i16j5mx60lkcy-pango-1.38.1.drv",["out"]),("/gnu/store/9hh2cmj6zabrr7acdmq03bmzsa12vrxp-perl-5.22.1.drv",["out"]),("/gnu/store/a2n2jp4q8yp2ss2dgk3av0bkyqkhjiz1-cups-filters-1.4.0.drv",["out"]),("/gnu/store/bzp5jkh7xgbjb1i2mm0is9bkx7p3fp7f-harfbuzz-1.0.6.drv",["out"]),("/gnu/store/fi41w9iaxi7fm22w55zj86yjbhs8fqf9-openssl-1.0.2f.drv",["out"]),("/gnu/store/fr65rd4r3rlch9r41cvf266wxcqmfbfj-gnome-session-3.18.1.2.drv",["out"]),("/gnu/store/gh2rxq397g7qmjpsg0qcni6pdnrp93a2-graphite2-1.3.5.drv",["out"]),("/gnu/store/i6yfwxiqn3awwg6fh44m5mw8hkq1c0jh-openssl-1.0.2f.drv",["out"]),("/gnu/store/imin0ijzdfg3pw2nirjwsxg086yxx4p2-module-import.drv",["out"]),("/gnu/store/lmxk7qlhqmycd3194d51m97spbhr06dh-perl-5.22.1.drv",["out"]),("/gnu/store/mh24bqnzini70k5s74j816q4jyqf2zmj-perl-5.22.1.drv",["out"]),("/gnu/store/nrw3x5vmk4fygvs7vgpci4pyhl6lwwkd-guile-2.0.11.drv",["out"]),("/gnu/store/r54za3ymsl5jlshhm9x8l1c590fgp68n-cups-2.1.0.drv",["out"]),("/gnu/store/riwksncgzzy1hfliarp6hlrvzgkk3285-perl-5.22.1.drv",["out"]),("/gnu/store/yp83gnlzc3kv8w338pij90rasr5bysx9-qpdf-5.1.3.drv",["out"]),("/gnu/store/zv162a9wn4752cfx7112c6whd7hsdx7k-gnome-desktop-3.18.1.drv",["out"]),("/gnu/store/zvl8f5d1vh7l19almlkqfgx6ig4qgh78-librsvg-2.40.13.drv",["out"])],["/gnu/store/60a5vinj56nhxzszfyayjjy61b303c8r-gnome-session-3.18.1.2-guile-builder"],"i686-linux","/gnu/store/77ipqajm5fyawv6fqrpm232k4qp6flik-guile-2.0.11/bin/guile",["--no-auto-compile","-L","/gnu/store/6xy20xcbxl6yzp5p2g28ly06yc36cxbl-module-import","/gnu/store/60a5vinj56nhxzszfyayjjy61b303c8r-gnome-session-3.18.1.2-guile-builder"],[("GUILE_LOAD_COMPILED_PATH","/gnu/store/lnixf02i03307hn5icfax083nal12bks-module-import-compiled"),("out","/gnu/store/dhrgkq1zfkkc5rnz51qlshakapsa2sgm-gnome-session-3.18.1.2"),("preferLocalBuild","1")])

      Mark