Make network access allowances exclusive

[MikeMcQuaid]

• Treat explicit phases as an allow-list so formulae can name only the phases requiring network access.
• Preserve no-argument behaviour and scalar or array inputs.

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OpenAI Codex 5.6 sol high with local review and testing.

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[p-linnane]

Nice!

[Copilot]

Pull request overview

Updates the Formula network-access DSL so explicit phases act as an exclusive allow-list while preserving existing inputs.

Changes:

• Denies unspecified phases.
• Adds coverage for selective and array-based allowances.
• Documents the updated behavior.
• Identified a moderate issue: invalid phases can mutate policy state before raising (3 votes).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Summary
Library/Homebrew/test/formula_spec.rb	Tests exclusive phase allowances.
Library/Homebrew/formula.rb	Implements the updated policy behavior; validation should occur before mutation.

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