One of our user used fenced code block with attribute but it raises an exception that is not catched:

Traceback (most recent call last):
  File "/usr/lib/python3.7/site-packages/roundup/cgi/client.py", line 1876, in renderContext
    result = pt.render(self, None, None, **args)
  File "/usr/lib/python3.7/site-packages/roundup/cgi/engine_jinja2.py", line 93, in render
    s = self._tpl.render(c)
  File "/usr/lib/python3.7/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/usr/lib/python3.7/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/usr/lib/python3.7/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "/home/roundup/html/issue.item.html", line 2, in top-level template code
    {% set bots = ['reviewbot', 'roundup-bot'] %}
  File "/home/roundup/html/layout/page.html", line 21, in top-level template code
    {% block page_content %}
  File "/home/roundup/html/layout/page.html", line 59, in block "page_content"
    {% block content %} {% endblock %}
  File "/home/roundup/html/issue.item.html", line 113, in block "content"
    <div class="msg">{{ utils.codereview_replace(utils.mercurial_replace(msg.content.markdown()))|u|safe }}</div>
  File "/usr/lib/python3.7/site-packages/roundup/cgi/templating.py", line 1733, in markdown
    return u2s(markdown(s2u(s)))
  File "/usr/lib/python3.7/site-packages/roundup/cgi/templating.py", line 72, in <lambda>
    markdown = lambda s: Markdown(safe_mode='escape', extras={ 'fenced-code-blocks' : True }).convert(s)
  File "/usr/lib/python3.7/site-packages/markdown2.py", line 366, in convert
    text = self._do_fenced_code_blocks(text)
  File "/usr/lib/python3.7/site-packages/markdown2.py", line 1883, in _do_fenced_code_blocks
    return self._fenced_code_block_re.sub(self._fenced_code_block_sub, text)
  File "/usr/lib/python3.7/site-packages/markdown2.py", line 1879, in _fenced_code_block_sub
    return self._code_block_sub(match, is_fenced_code_block=True)
  File "/usr/lib/python3.7/site-packages/markdown2.py", line 1824, in _code_block_sub
    **formatter_opts)
TypeError: _color_with_pygments() argument after ** must be a mapping, not bool


I think this should not prevent roundup to render the message as plain text.