merge repo into monorepo at prefix with history

merge-repo.sh

#!/usr/bin/env bash
remote_name=my-repo
[email protected]:my-org/my-repo.git
remote_branch=master
prefix=packages/$remote_name/ # trailing slash is important

git remote add $remote_name $remote_url
git fetch $remote_name
# create a merge commit with our side winning as the strategy but stop before committing it
git merge -s ours --allow-unrelated-histories --no-commit $remote_name/$remote_branch
# read tree into index with a prefix and update the working tree
git read-tree --prefix=$prefix -u $remote_name/$remote_branch
# now commit the merge commit
git commit -m "merge $remote_name/$remote_branch"