You can clone with
I am viewing http://reddit.com/domain/twitter.com/ and all is well. Then I click the "new" tab and I go to http://reddit.com/domain/twitter.com/new and I start seeing posts from all subreddits. Switching my "new" view from "rising" to "new" fixes the problem temporarily and by default, but going to http://reddit.com/domain/twitter.com/new?sort=rising still yields the incorrect behavior.
I'm seconding this issue. (Is there a way to star issues or something on Github?)
Definitely still exists. http://www.reddit.com/domain/quickmeme.com/new/ shows URLs not just from quickmeme.com
Confirming still an active issue.