By default you can close issues from commit messages by saying 'Closes #12' or 'Fixed #101'.
If a commit message matches the regular expression below, all issues referenced from
the matched text will be closed. This happens when the commit is pushed or merged
into the default branch of a project.
If you want to customize the message please do so in [gitlab.yml](https://gitlab.com/gitlab-org/gitlab-ce/blob/73b92f85bcd6c213b845cc997843a969cf0906cf/config/gitlab.yml.example#L73)
When not specified, the default issue_closing_pattern as shown below will be used: