This is a special function only designed for calculating diff between the current pipeline commit, passed by the CI_COMMIT_SHA env var in your gitlab job and a defined other branch (in the gipgee case normally the CI_DEFAULT_BRANCH) It assumes, that the originBranch exists as reference remotes/origin/<originBranch> To ensure this, you need to set the GIT_DEPTH variable to 0 in your .gitlab-ci.yml to avoid a shallow clone which does not contain the other branch.