Step 1.
Fetch the code and create a new branch pointing to it
git fetch http://softwarepublico.gov.br/gitlab/leandroarndt/e-sic-livre.git issue_12
git checkout -b leandroarndt/e-sic-livre-issue_12 FETCH_HEAD
Step 2.
Merge the branch and push the changes to GitLab
git checkout master
git merge --no-ff leandroarndt/e-sic-livre-issue_12
git push origin master