get_branch return always "HEAD"

[svensq]

Function get_branch return always "HEAD" in GitLab CI.

[brejoc]

Looks like this is a known issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/19421

[brejoc]

@svensq Btw, how does your work-around look like?

[svensq]

I use the environment variable "CI_COMMIT_REF_SLUG" of GitLab: https://docs.gitlab.com/ee/ci/variables/#predefined-variables-environment-variables