Return a unicode string with the traceback as rendered HTML.

def render_as_html(self, full=False):
        """Return a unicode string with the traceback as rendered HTML."""
        from jinja2.debugrenderer import render_traceback
        return u'%s\n\n<!--\n%s\n-->' % (
            render_traceback(self, full=full),
            self.render_as_text().decode('utf-8', 'replace')
        )