Delete copilot/* branches in E2E test workflow

[Copilot]

• Update "Clean up issues and pull requests" step in main branch's test.yml to delete PR branches
• Test bash logic for correctness and edge cases
• Code review completed and addressed
• Address feedback:
  • Move branch extraction after gh pr close (closer to where it's used)
  • Move || true inside $() for proper error handling
  • Add TESTING_REPOSITORY environment variable to avoid hardcoding
  • Use environment variable in both the scan step and branch deletion
  • Use gh api instead of git push for consistent authentication context

The implementation:

• Extracts branch name from each PR using gh pr view "$URL" --json headRefName -q .headRefName || true
• Deletes the branch after closing the PR using gh api -X DELETE "repos/${{ env.TESTING_REPOSITORY }}/git/refs/heads/$branch"
• Handles failures gracefully with || true inside command substitution
• Uses centralized TESTING_REPOSITORY environment variable for consistency
• Uses gh api for branch deletion to maintain consistent authentication context with other gh CLI commands

Note: Similar changes will need to be applied to v1 and v2 branches separately after this PR is merged.

Original prompt

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This section details on the original issue you should resolve

<issue_title>[Task] Delete copilot/* branches in E2E test workflow</issue_title>
<issue_description>### Problem

Before transferring the action to github/accessibility-scanner, I deleted thousands of copilot/* branches by running git branch -r | grep -Eo 'copilot/.*' | xargs -I {} git push origin :{}. This took more than 30 minutes to complete.

Because of https://github.com/github-community-projects/continuous-ai-for-accessibility-scanner/pull/2202 ¹, the new github/accessibility-scanner repo will never have thousands of defunct copilot/* branches…but github/accessibility-scanner-testing will. It’s already starting.

Solution

• In main’s test.yml, v2’s test.yml, and v1’s test.yml update the “Clean up issues and pull requests” step to also delete the branch for each PR it deletes.
  • Do not use git branch -r | grep -Eo 'copilot/.*' | xargs -I {} git push origin :{} to delete all Copilot branches—that is too broad, and it could delete branches unrelated to E2E testing (i.e. branches we want to keep).
  • The gh CLI doesn’t have a command or flag for deleting branches alongside PRs, but something like this should work: branch="$(gh pr view <PR-number> --json headRefName -q .headRefName)" && [ -n "$branch" ] && git push origin --delete "$branch" || true.

Comments on the Issue (you are @copilot in this section)

Fixes github/continuous-ai-for-accessibility#76

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Footnotes

1. And https://github.com/github/accessibility-scanner/pull/7/files#diff-faff1af3d8ff408964a57b2e475f69a6b7c7b71c9978cccc8f471798caac2c88 and https://github.com/github/accessibility-scanner/pull/8/files#diff-faff1af3d8ff408964a57b2e475f69a6b7c7b71c9978cccc8f471798caac2c88</issue_description> ↩

[Copilot]

Pull Request Overview

This PR adds automatic deletion of PR branches during E2E test cleanup to prevent accumulation of defunct copilot/* branches. The changes introduce branch deletion logic that extracts the branch name from each PR and removes it after closing the PR.

• Adds TESTING_REPOSITORY environment variable for centralized repository configuration
• Implements branch extraction and deletion logic in the cleanup workflow
• Updates repository reference to use the new environment variable

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