`qa/selectors` job uses a different Ruby version on merge requests.
On 16.6, the Ruby version defined is 3.0, however the qa:selectors
job uses Ruby 3.1 at merge request level:
On the merge request job Ruby 3.1 is used: https://gitlab.com/gitlab-org/gitlab/-/jobs/7176076861
Using docker image sha256:305dddf2c8b207c2f22302f0f7dd927aada3e0b3b42b85237f9955bbd6db1707 for registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.1:bundler-2.3-chrome-113-docker-24.0.5 with digest registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.1@sha256:1f53da1ea093858a076d4c39c46ee762359045b3b74c667408d0374236e14ded
On the stable branch Ruby 3.0 is used: https://gitlab.com/gitlab-org/gitlab/-/jobs/7175908878
Using docker image sha256:8c561f07127a06a684dbafd1870204c7afaa4079a38e44c62edb7e33bc85c5de for registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.0:bundler-2.3-chrome-113-docker-24.0.5 with digest registry.gitlab.com/gitlab-org/gitlab-build-images/debian-bullseye-ruby-3.0@sha256:3837a4ed44d606823430bcdb3f8b2d776bb86ee8cb6e8ab1d75772891a871c42 .
The disparity caused a false positive when validating a backport for 16.6, gems compatible with ruby 3.1 were installed on !155270 (merged), which led to floating dependency issues !157205 (merged), !157205 (merged)
The problem might be specific to older versions that still support Ruby 3.0. This issue aims to investigate if there is a Ruby incompatibility on recent versions, to analyze and fix the problem.