cross: Fix shebang of installed python scripts

[symphorien]

An alternative to the below PR

Closes: #449340
Fixes: #449325

It uses a patch to installer that was accepted upstream, then reverted because it was too much functionality and if somebody wants it they should implement a different frontend to the installer command using installer as a library. For now we just need one more CLI flag so the burden of carrying this patch is lower to the one of copy pasting the CLI part of installer with the patch.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

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[RossComputerGuy]

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 462993 --package pkgsLLVM.python313Packages.pytest
Commit: 45781cc53ed1d218bae636a4c75d61f4457e38f0

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aarch64-linux

❌ 3 packages failed to build:

• pkgsLLVM.python313Packages.pytest
• pkgsLLVM.python313Packages.pytest.dist (pkgsLLVM.python313Packages.pytest.dist.dist, pkgsLLVM.python313Packages.pytest.dist.testout)
• pkgsLLVM.python313Packages.pytest.testout (pkgsLLVM.python313Packages.pytest.testout.dist, pkgsLLVM.python313Packages.pytest.testout.testout)

[RossComputerGuy]

For whatever reason, nixpkgs-review refused to build it. It tried and then killed it in the middle of the import check. I'm running a build manually right now.

[symphorien]

maybe it's because it's failing the formatting ci so it can't reuse the evaluation from ci?

[RossComputerGuy]

But wouldn't it have not built it? It tried building the derivation, stopped half way through with no error in the nix build, and then nixpkgs-review tried getting the logs but failed (presumably because the build didn't finish).

[RossComputerGuy]

I was able to build the derivation from the issue, this should be gtg once CI is green.