Merge pull request #259074 from tweag/detect-merge-conflicts

    # as specified in nixos/release-combined.nix

    runs-on: ubuntu-latest

    steps:

      - name: Resolving the merge commit

        run: |

          if result=$(git ls-remote --exit-code ${{ github.event.pull_request.base.repo.clone_url }} refs/pull/${{ github.event.pull_request.number }}/merge); then

            mergedSha=$(cut -f1 <<< "$result")

            echo "The PR appears to not have any conflicts, checking the merge commit $mergedSha"

          else

            echo "The PR may have a merge conflict"

            exit 1

          fi

          echo "mergedSha=$mergedSha" >> "$GITHUB_ENV"

      - uses: actions/checkout@v4

        with:

          # pull_request_target checks out the base branch by default

          ref: refs/pull/${{ github.event.pull_request.number }}/merge

          ref: ${{ env.mergedSha }}

          # Fetches the merge commit and its parents

          fetch-depth: 2

      - name: Determining PR git hashes

        run: |

          echo "mergedSha=$(git rev-parse HEAD)" >> "$GITHUB_ENV"

          # For pull_request_target this is the same as $GITHUB_SHA

          echo "baseSha=$(git rev-parse HEAD^1)" >> "$GITHUB_ENV"