fixup! ci: cancel overridden workflows (XRPLF#4597)

.github/workflows/nix.yml

@@ -156,6 +156,7 @@ jobs:
           # fail. However, Github will probably prevent the job from
           # running at all.
           git log --oneline
+          git config --global --add safe.directory "${GITHUB_WORKSPACE}"
           git merge --no-commit --no-edit -v \
             ${{ github.event.pull_request.base.sha }}
           git diff || true