Not github, but you may be interested in <a href="http:&#x2F;&#x2F;phabricator.org&#x2F;" rel="nofollow">http:&#x2F;&#x2F;phabricator.org&#x2F;</a>. We hired a guy a while back who swore by it. We had too much momentum in github, so it did not catch on at our org. One of his favorite features, if I recall as it was a few years ago, is what you are talking about.