texlive.withPackages: respect .outputSpecified even for old style packages

[xworld21]

Description of changes

First subtle sharp edge in the backward compatibility code: when detecting .pkgs = [ ... ], we assume that the package is in the old format and convert it. However, if an output was specified, we lose that information.

Since specifying an output only makes sense for new style packages, we can and must disable conversion in those cases.

Example:

texlive.withPackages (ps: [ perlPackages.LaTeXML.tex ])

should install the TeX files of LaTeXML in the environment, and nothing else. Right now LaTeXML gets re-converted to the new style (due to the still present .pkgs) and you get both binaries and TeX files.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• 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/)
• 23.11 Release Notes (or backporting 23.05 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.

[xworld21]

@veprbl I forgot to tag you here: this fixes a bug compared to the behaviour I claim in the new docs.