pre-build-hook is ignored on MacOS

[arianvp]

Describe the bug

It seems pre-build-hook has no effect on MacOS even though MacOS supports sandbox = true and extra-sandbox-paths

Steps To Reproduce

nix build --pre-build-hook my-hook

Expected behavior

It should fail because my-hook doesn't exist. but it succeeds because the hook isn't executed

Metadata

Additional context

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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