pythonInterpreters.pypy310_prebuilt: set mainProgram

[trofi]

Without the change the eval fails as:

$ nix build --no-link -f. pythonInterpreters.pypy310_prebuilt.tests.test-packageOverrides
error:
   … in the condition of the assert statement
     at pkgs/development/interpreters/python/tests.nix:212:11:
      211|           in
      212|           assert myPython.pkgs.foobar == myPython.pkgs.numpy;
         |           ^
      213|           myPython.withPackages (ps: with ps; [ foobar ]);

   … while evaluating the attribute 'outPath'
     at lib/customisation.nix:421:7:
      420|         drv.drvPath;
      421|       outPath =
         |       ^
      422|         assert condition;

   (stack trace truncated; use '--show-trace' to show the full, detailed trace)

   error: attribute 'mainProgram' missing
   at pkgs/by-name/me/meson/package.nix:75:52:
       74|           --replace-fail "PythonExternalProgram('python3', mesonlib.python_command)" \
       75|                          "PythonExternalProgram('${python3.meta.mainProgram}', mesonlib.python_command)"
         |                                                    ^
       76|         substituteInPlace mesonbuild/modules/python3.py \

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/)
• Nixpkgs 25.11 Release Notes (or backporting 24.11 and 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
• NixOS 25.11 Release Notes (or backporting 24.11 and 25.05 NixOS Release notes)
  • (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.

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[nixpkgs-ci]

Successfully created backport PR for release-25.05:

• [Backport release-25.05] pythonInterpreters.pypy310_prebuilt: set mainProgram #412927