test(import): fully isolate git config in author fallback test

[gtrrz-victor]

https://entire.io/gh/entireio/cli/trails/935

Stacked on #1846.

Summary

Copilot flagged that TestRun_UnconfiguredGitIdentityFallsBackToDefaults (added in #1846) only overrides HOME/XDG_CONFIG_HOME. But checkpoint.GetGitAuthorFromRepo resolves GlobalScope through go-git's Auto loader, which also honors GIT_CONFIG_GLOBAL and the system /etc/gitconfig. On any dev machine or CI image where either carries a git identity (e.g. GIT_CONFIG_GLOBAL set by chezmoi/direnv — the same dotfile-tool setups configloader.go exists to handle), the Unknown/unknown@local assertion would flake.

The fix neutralizes every global source, matching the checkpoint package's own pointHomeAt helper (checkpoint/configloader_test.go:52, checkpoint/global_test.go:39):

• GIT_CONFIG_NOSYSTEM=1 — skip /etc/gitconfig
• unset GIT_CONFIG_GLOBAL — fall back to XDG (empty value would disable global config entirely, so it is unset, not emptied)

Production code is unchanged; this is test-isolation hardening only. The sibling TestRun_StampsImporterGitAuthorOnCheckpointCommit was never at risk — it uses repo-local identity, which wins go-git's config merge regardless of global/system.

Test plan

• go test ./cmd/entire/cli/agentimport/ -run 'TestRun_Unconfigured...|TestRun_Stamps...' -count=1 green
• golangci-lint (v2.11.3) 0 issues

🤖 Generated with Claude Code

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Note

Low Risk
Test-only comment and environment setup; no runtime behavior changes.

Overview
Hardens TestRun_UnconfiguredGitIdentityFallsBackToDefaults so it no longer flakes when the host has git identity outside HOME/XDG_CONFIG_HOME.

The test now sets GIT_CONFIG_NOSYSTEM=1 and unsets GIT_CONFIG_GLOBAL (after t.Setenv for cleanup), matching the checkpoint package’s pointHomeAt helper. That blocks go-git’s global config sources (/etc/gitconfig, GIT_CONFIG_GLOBAL, etc.) so Unknown / unknown@local assertions stay reliable. Comments were expanded to document why full isolation is required.

No production code changes — test isolation only.

^{Reviewed by Cursor Bugbot for commit 3dda7ee. Configure here.}

[Copilot]

Pull request overview

Hardens entire import’s author-fallback unit test so it’s fully isolated from any host/global Git identity configuration, preventing flakes caused by go-git’s global config resolution behavior.

Changes:

• Expanded the test comment to document why additional git config isolation is required.
• In TestRun_UnconfiguredGitIdentityFallsBackToDefaults, set GIT_CONFIG_NOSYSTEM=1 and explicitly unset GIT_CONFIG_GLOBAL (while still restoring it after the test via t.Setenv).