import os


def get_latest_commit(repo):
    if repo.head.is_detached:
        return repo.head.commit
    else:
        return repo.head.ref.commit


def get_deploy_message(repo):
    old_msg = get_latest_commit(repo).message
    return "{old_msg}\n" \
           "\n" \
           "Build branch {branch} ({hexsha}) from {repo_name}" \
        .format(old_msg=old_msg,
                branch=os.environ['REF_NAME'],
                hexsha=get_latest_commit(repo).hexsha[0:7],
                repo_name='latex/latex-packages')