Link to the issue number on GitHub within a commit message
Just include #xxx in your commit message to reference an issue without closing it.
With new GitHub issues 2.0 you can use these synonyms to reference an issue and close it (in your commit message):
fix #xxxfixes #xxxfixed #xxxclose #xxxcloses #xxxclosed #xxxresolve #xxxresolves #xxxresolved #xxx
You can also substitute #xxx with gh-xxx.
Referencing and closing issues across repos also works:
fixes user/repo#xxxCheck out the documentation available in their Help section.
If you want to link to a GitHub issue and close the issue, you can provide the following lines in your Git commit message:
Closes #1.Closes GH-1.Closes gh-1.(Any of the three will work.) Note that this will link to the issue and also close it. You can find out more in this blog post (start watching the embedded video at about 1:40).
I'm not sure if a similar syntax will simply link to an issue without closing it.
github adds a reference to the commit if it contains #issuenbr (discovered this by chance).