get config from actual branch if not defined
2020-06-11 20:35:41,761(CRITI) ArtifactSrc: error calling 'https://gitlab.com/Orange-OpenSource/lfn/ci_cd/chained-ci/raw/chained-ci-py-migration/pod_config/certificats/terrahouat_creds.yml': '404'
ArtifactSrc: error calling 'https://gitlab.com/Orange-OpenSource/lfn/ci_cd/chained-ci/raw/chained-ci-py-migration/pod_config/certificats/terrahouat_creds.yml': '404'```
Do not use ```master``` if a local gitlab vars specify the actual branch