Acceptance tests for the simp-rake-helpers gem always fail when run from the GitLab CI pipeline, even when they succeed in Travis CI.
Note that, unlike other SIMP acceptance tests, simp-rake-helpers uses beaker's docker "hypervisor"―not vagrant/virtualbox. As a result, both Travis can run these jobs on its public infrastructure along with the other stages. It's unlikely that GitLab CI can run nested docker containers within its publically-hosted docker executors.
An example from a recent pipeline:
Travis acceptance tests succeeded: https://travis-ci.org/github/simp/rubygem-simp-rake-helpers/builds/689338724
GitLab CI acceptance tests failed: https://gitlab.com/simp/rubygem-simp-rake-helpers/-/jobs