This is basically a puzzle that you can solve by using some basic Git and Docker skills:
- Clone this repository
- Checkout the branch named branch-a
- Rebase on master
- Checkout the master branch
- Merge the branch named branch-a to the current branch
- Merge (with --squash) the branch named branch-b to the current branch
- Use docker compose to run from the root of the repository
- Observe the message that is output
If the message makes sense, then you have done it!