def get_project_content_commit_date(root_dir='.', exclusions=None):
    logger = logging.getLogger(__name__)
    extensions = ('rst', 'ipynb', 'png', 'jpeg', 'jpg', 'svg', 'gif')
    content_paths = []
    for extname in extensions:
        content_paths += get_filepaths_with_extension(
            extname,
            root_dir=root_dir)
    exclude = Matcher(exclusions if exclusions
                      else ['readme.rst', 'license.rst'])
    content_paths = [p for p in content_paths
                     if not (exclude(p) or exclude(p.split(os.path.sep)[0]))]
    logger.debug('Found content paths: {}'.format(', '.join(content_paths)))
    if not content_paths:
        raise RuntimeError('No content files found in {}'.format(root_dir))
    commit_datetimes = []
    for filepath in content_paths:
        try:
            datetime = read_git_commit_timestamp_for_file(
                filepath,
                repo_path=root_dir)
            commit_datetimes.append(datetime)
        except IOError:
            logger.warning(
                'Could not get commit for {}, skipping'.format(filepath))
    if not commit_datetimes:
        raise RuntimeError('No content commits could be found')
    latest_datetime = max(commit_datetimes)
    return latest_datetime