The recent merge from added a variables: block in pupmod-simp-auditd's puppet(sync)-managed portion of .gitlab-ci.yml that preempted the common YAML anchors such as pup_5 in acceptance tests. This caused the acceptance tests to fail, because the variables: provided by the YAML anchors were missing, leaving PUPPET_VERSION: UNDEFINED, which cauded bundler to fail before executing the tests. The global PUPPET_VERSION: UNDEFINED was removed in order to get the tests to run.
However, the global UNDEFINED value is an intentional canary, designed to fail the job if the yaml anchor's variables section goes missing. If PUPPET_VERSION: UNDEFINED the acceptance tests will silently misconfigure themselves and run without the intended settings.