Return a list of content types in a repository.

    :param Repo repo:
        The git repository.
    :returns: list

def list_content_types(repo):
    """
    Return a list of content types in a repository.

    :param Repo repo:
        The git repository.
    :returns: list
    """
    schema_files = glob.glob(
        os.path.join(repo.working_dir, '_schemas', '*.avsc'))
    return [os.path.splitext(os.path.basename(schema_file))[0]
            for schema_file in schema_files]