branchprotector: remove protection from excluded branches

[kaovilai]

Fix issue where excluded branches retain existing protection instead of being removed.

When a branch is added to the exclude list in branchprotector configuration, the tool
correctly stops applying new protection rules but does not remove existing protection
from branches that were previously protected.

This change adds logic to detect excluded branches that are currently protected and
queue them for removal by sending requirements with Request: nil, which triggers
RemoveBranchProtection() in the configureBranches() function.

The fix prevents push failures like:
remote: error: GH006: Protected branch update failed for refs/heads/konflux-branch
remote: - Changes must be made through a pull request.

Changes:

• Add detection logic for excluded protected branches in UpdateRepo()
• Send removal requests (Request: nil) for such branches
• Update tests to expect removal requests for excluded protected branches
• Add code comment explaining the call flow to RemoveBranchProtection

Fixes #477

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[k8s-ci-robot]

Hi @kaovilai. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: kaovilai
Once this PR has been reviewed and has the lgtm label, please assign petr-muller for approval. For more information see the Code Review Process.

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[petr-muller]

/ok-to-test

[Prucek]

Why is this map needed?

[kaovilai]

Problem

The allBranches slice can contain duplicate entries for the same branch because it's populated from two separate API calls:

  for _, onlyProtected := range []bool{false, true} { // runs twice
      bs, err := p.client.GetBranches(orgName, repoName, onlyProtected)
      allBranches = append(allBranches, bs...) // can add same branch twice
  }

Without Deduplication

If a branch like konflux-test appears in both API responses, we would send two removal requests:

1. First iteration: {Org: "org", Repo: "repo", Branch: "konflux-test", Request: nil}
2. Second iteration: {Org: "org", Repo: "repo", Branch: "konflux-test", Request: nil}

With seen Map

  if b.Protected && branchExclusions.MatchString(b.Name) && !seen[b.Name] {
      seen[b.Name] = true  // Mark as processed
      // Send removal request only once
  }

The seen map ensures each excluded protected branch gets exactly one removal request, regardless of how many times it appears in allBranches.

This prevents:

• Duplicate API calls to GitHub
• Confusing log messages
• Potential race conditions in the removal process

[kaovilai]

Perhaps if p.client.GetBranches(orgName, repoName, false) return all branches we can initialize allBranches once.

[Prucek]

okay, get it. Thanks!

[Prucek]

/lgtm