Introducing Issue Mentions

With Issues 2.0 and GFM, it is easy to link to users, issues and commits from issue comments:

You can also mention issues directly from commit messages, and the mentioned issue will link back to the commit:

Now, the same is true when you mention an issue or pull request from another issue. For example, this issue mentions pull #1748:

The pull request will now link back to the mentioning issue: