If ``single_pull`` is enabled, saves the current git hash of the specified repository/branch combination,
        to indicate that it shouldn't be pull again.

def save_hash(self, repo: str, branch: str, git_repo: Repo):
        """
        If ``single_pull`` is enabled, saves the current git hash of the specified repository/branch combination,
        to indicate that it shouldn't be pull again.
        """
        if self.single_pull:
            repo_id = self.repo_id(repo)
            self._current_hashes[repo_id][branch] = git_repo.head.object.hexsha