if [ "$old" = "0000000000000000000000000000000000000000" ]; then # new branch
commits="created with $(git describe --always "$new")"
elif [ "$new" = "0000000000000000000000000000000000000000" ]; then # deleted branch
if [ "$old" = "0000000000000000000000000000000000000000" ]; then # new branch
commits="created with $(git describe --always "$new")"
elif [ "$new" = "0000000000000000000000000000000000000000" ]; then # deleted branch
else # commit --amend, rebase, or similar
commits="!! rewrote history from $(git describe --always "$(git merge-base "$old" "$new")") -> $(git describe --always "$new") erasing history through $(git describe --always "$old")"
fi
else # commit --amend, rebase, or similar
commits="!! rewrote history from $(git describe --always "$(git merge-base "$old" "$new")") -> $(git describe --always "$new") erasing history through $(git describe --always "$old")"
fi