nukeReferences: fix for store paths with special characters

[veprbl]

Motivation for this change

I'm running nix with store directory in a custom path containing a '+' character. This prevents nukeReferences from working properly because some characters in the path get interpreted as a regular expression special characters. Broken nukeReferences will prevent python3 from building on my setup because it requires disallowedReferences = [ openssl.dev ];.

The proposed fix implements escaping of the special characters in the store path.

Things done

Tested with

with import <nixpkgs> {};

stdenvNoCC.mkDerivation {
  name = "nuke-refs-test";

  nativeBuildInputs = [ nukeReferences ];

  buildCommand = ''
    cat > $out <<EOF
    out: $out
    openssl: ${openssl}
    python: ${python}
    EOF
    nuke-refs -e ${openssl} $out
    echo
    echo "> Only out and python should be nuked:"
    cat "$out"

    echo
    echo "> This should fail:"
    nuke-refs -e /not/a/path $out
  '';
}

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

---

[veprbl]

@volth Could you please look at this? I think this is correct, but I don't have much experience with Perl.