make release with modifications should fail

We should probably stop if there are any important modifications, to avoid extra files that can't be recreated from the repo. Could also do this in another copy like

export GIT_DIR=$(realpath $(git rev-parse --git-dir)); cd $(mktemp -d); git checkout -f; ls

Reproduce the release with local modifications using the repository state and command shown in the issue. Trace the release entry point to identify where repository cleanliness is checked. Done means a release with important uncommitted modifications fails instead of producing files that cannot be recreated.