discourse/.github/workflows/check-branches.yml

name: PR base branch check
on:
  pull_request:
jobs:
  check-branches:
    if: github.event_name == 'pull_request' && github.repository == 'discourse/discourse-private-mirror'
    runs-on: ubuntu-latest
    steps:
      - name: Check branches
        run: |
          BASE_REF=${{ github.base_ref }}
          if [ "$BASE_REF" == "tests-passed" ]; then
            echo "PR requests to tests-passed branch are not allowed. Please use main."
            exit 1
          fi