def update(self, folder, git_repository):
        """Creates or updates theme folder according given git repository.

        :param git_repository: git url of the theme folder
        :param folder: path of the git managed theme folder
        """
        # git clone
        try:
            self.clone(folder, git_repository)
        # git update if folder already exist
        except OSError:
            self.update_git_repository(folder, git_repository)
            self.pull(folder)
Creates or updates theme folder according given git repository.

        :param git_repository: git url of the theme folder
        :param folder: path of the git managed theme folder