# actions/checkout did a merge checkout of the pull-request. As such, the first
        # commit is the merge commit. This means that on HEAD^ is the base branch, and
        # on HEAD^2 are the commits from the pull-request. We now check if those trees
        # have a common parent. If not, we fetch a few more commits till we do. In result,
        # the log between HEAD^ and HEAD^2 will be the commits in the pull-request