Failing test for not recognizing a welcome message.

See https://github.com/izidormatusov/gg_scraper/commit/75559fc4d3b5d84c75d0b100361f523452c7e78d
Ignore links in welcome message

Some groups, e.g. django-oscar [1], have links in welcome message. Those
are not supposed to be a link to the next page, ignore them.

1: https://groups.google.com/forum/#!forum/django-oscar