[MikeMcQuaid]

Preserve mirror remotes unless users explicitly select defaults.

Fixes #24364

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Codex with GPT 6 Astra at Extra High effort, with local review and testing.

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[coderabbitai]

No actionable comments were generated in the recent review.

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Commits

Reviewing files that changed from the base of the PR and between 9999947 and 745e907.

Files selected for processing: 3

• Library/Homebrew/cmd/update.sh
• Library/Homebrew/test/cmd/update_spec.rb
• docs/Installation.md

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📝 Summary

Summary by CodeRabbit

• Bug Fixes
  • brew update now respects explicitly selected brew and core remotes, including when they match the default remotes. This applies to regular updates and automatic updates.
• Documentation
  • Updated installation guidance to clarify how mirror settings affect installation and later updates, and added commands for resetting both repositories to their GitHub remotes.

The update script now checks whether brew and core remote variables were explicitly set, even when their values match the defaults. Tests cover remote selection, and the installation guidance explains how unset variables affect installation and later updates.

Changes: Remote selection and reset

Layer / File(s)	Summary
Remote selection and reset behavior Library/Homebrew/cmd/update.sh, Library/Homebrew/test/cmd/update_spec.rb, docs/Installation.md	The update script checks explicit brew and core remote settings, including settings equal to the defaults. Parameterised tests cover explicit and implicit defaults, non-default remotes, and regular and --auto-update runs. Installation guidance describes the behavior of unset mirror variables and gives commands to reset both remotes to their GitHub URLs.

Priority: Normal

Severity of issue fixed: Medium

Merge Risk: Minimal · up to 745e9

The change is mergeable after normal checks; no actionable remote-reset risk remains in the reviewed evidence.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly describes the main change: allowing users to reset Git remotes to their default repositories.
Description check		The description explains the remote-preservation behaviour, references the related issue, and confirms relevant tests and validation steps.
Linked Issues check		Issue #24364 requires explicit default values to reset the local brew and core Git remotes while preserving mirror remotes when the variables are implicit. update.sh now checks `HOMEBREW_USER_SET_VA…
Out of Scope Changes check		The changed files support the linked issue. The shell change implements explicit remote selection. The tests verify the reset and preservation behaviour. The installation documentation explains the be…

Full details: Linked Issues check

Explanation

Issue #24364 requires explicit default values to reset the local brew and core Git remotes while preserving mirror remotes when the variables are implicit. update.sh now checks HOMEBREW_USER_SET_VARS for both remote variables. The update logic therefore applies an explicit default and retains an implicit default's existing remote. update_spec.rb tests explicit defaults, implicit defaults, non-default remotes, and both normal and --auto-update paths.

Full details: Out of Scope Changes check

Explanation

The changed files support the linked issue. The shell change implements explicit remote selection. The tests verify the reset and preservation behaviour. The installation documentation explains the behaviour and gives reset commands. No unrelated change is evidenced.

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[ZhongRuoyu]

Thanks!