1. Create new branch:

git checkout -b otherrepo-master master

2. Get the contents of the PR

git pull https://github.com/otherrepo/my-repo-name.git master

3. Change back to master

git checkout master

4. Now DO NOT merge the whole branch, BUT cherry-pick exactly the commits from the other branch.

The hash uniquely defines the commit - regardless of the branch it is in.

git cherry-pick abc0123

5. Check, remove the temp branch, push

git log
git branch -D otherrepo-master
git push origin master