Enable set_up_git_repo to set-up the repos for different situation
    
    These situations can be:
    - FF: the pull-request can be fast-forwarded from a repo to the other
    - merge: the pull-request can be merged (with a merge commit) from a
      repo to the other
    - conflicts: the pull-request cannot be merged from repo to the other
      due to conflicts
    - nochanges: there is nothing to merge between the two repos