mozilla/nunjucks — pull request #304 by cahnory (2014-10-20 13:39:05+00:00)
Title: Update `default` filter

Add the `boolean` argument documented in http://jinja.pocoo.org/docs/dev/templates/#default.

I wonder if `null` should be treated as undefined. (see https://github.com/mitsuhiko/jinja2/blob/master/jinja2/filters.py#L267)