fix(ci): remove --depth=1 from legacy guard base fetch

[prekshivyas]

Summary

The legacy-path-guard CI job fails on every PR with fatal: origin/main...HEAD: no merge base.

Root cause: The checkout uses fetch-depth: 0 (full PR history), but then git fetch origin main --depth=1 creates a shallow reference for origin/main with only 1 commit. Git can't find a merge base between the shallow main ref and HEAD.

Fix: Remove --depth=1 from the base branch fetch so origin/main has enough history for the three-dot diff.

Related

Introduced in #1683

Test plan

• This PR's own legacy-path-guard job passes (self-validating)

Signed-off-by: Prekshi Vyas prekshiv@nvidia.com

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Updated internal CI/CD workflow configuration to improve git history fetching for automated checks.

[coderabbitai]

📝 Walkthrough

Walkthrough

A workflow step in the GitHub Actions pipeline is modified to remove the --depth=1 shallow fetch limitation, enabling full commit history retrieval from the base branch during the "Fetch base branch" step.

Changes

Cohort / File(s)	Summary
GitHub Actions Workflow .github/workflows/legacy-path-guard.yaml	Removed --depth=1 flag from git fetch command in "Fetch base branch" step, changing from shallow to full history fetch for origin/${{ github.base_ref }}.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 No shallow wells for history's tale,
Full depth now flows without avail,
The git roots run deep and wide,
Base branch secrets come to confide! 🌿

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: removing the --depth=1 flag from a git fetch command in the legacy-path-guard CI workflow.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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