Issue closing does not work with branches

1. add a issue to GitLab
2. git clone repo
3. create a branch (e.g. git checkout -b new-branch)
4. push the branch to GitLab (e.g. `git push --set-upstream origin new-branch)
5. make changes
6. commit changes with issue closing tag (e.g. git commit -m "fixed closes #2 (closed)")
7. issue remains open on GitLab