sane_backends: disable parallel install

[symphorien]

for some reason that prevents libsane from finding plugins

Fixes #224569

I find this solution hard to believe, please double check.

Description of changes

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandbox = true set in nix.conf? (See Nix manual)
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 23.05 Release Notes (or backporting 22.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

[Artturin]

Do a diffoscope before and after this change maybe that'll reveal the issue

[symphorien]

diffoscope --html report.html --diff-mask 'cb76rxa72qn4pw6c54ha014hh08p3mw9|k05n99qgzjydsy7855asrndss345b2ix' fixed_sane broken_sane

https://blitiri.xlumurb.eu/~/report.html

I see no meaningful change, and yet I double checked with nixos-rebuild build-vm that I get a listing with this commit and not without. This makes no sense.

[symphorien]

Ah there is actually a difference hidden deep in the diff: the broken sane has one more symlik:

$  ls {broken,fixed}_sane/lib/{sane/,}libsane.so.1 -lah
ls: impossible d'accéder à 'fixed_sane/lib/sane/libsane.so.1': No such file or directory
lrwxrwxrwx 31 root root 16  1 janv.  1970 broken_sane/lib/libsane.so.1 -> libsane.so.1.2.1
lrwxrwxrwx 35 root root 26  1 janv.  1970 broken_sane/lib/sane/libsane.so.1 -> libsane-xerox_mfp.so.1.2.1
lrwxrwxrwx 31 root root 16  1 janv.  1970 fixed_sane/lib/libsane.so.1 -> libsane.so.1.2.1

and a symlink from libsane.so to libsane-xerox_mfp.so does not make sense. maybe it breaks everything.

[Artturin]

Let's add that to the comment and merge

[RaitoBezarius]

After the comment on diffoscope stuff is added, let's merge.

[VShell]

Having been trying to work this out today separately, I found the following comment suggesting the generation of this file is an issue with how they use libtool:

https://gitlab.com/sane-project/backends/-/blob/90cc6b1fb73212cec32196d4c0a66568b2130eec/backend/Makefile.am#L114-116

It'd seem the file is getting regenerated some time after that rm with parallel install.

[symphorien]

Fixed the comment.

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/brother-scanner-no-longer-recognized-by-scanimage/27183/6