git log -1 --pretty=%B | pbcopy # Can also specify -2 for last two messages.
git branch -l master main
# Do it all in one step
git fetch --all && git rebase -i origin/$(git branch -l master main)
git commit --reuse-message=HEAD@{1}
# shorter version
git commit -C HEAD@{1}
# even shorter!
git commit -C@@{1}