Backend: git push option `merge_request.merge_when_pipeline_succeeds` does not use merge trains.
Summary
When a project is set with Enable merge trains git push option merge_request.merge_when_pipeline_succeeds does a Merge Immediately instead of adding to a merge train.
Steps to reproduce
Video of reproduction https://youtu.be/Ka0CNs3pISc (gitlab unfiltered private).
Example Project
https://gitlab.com/bdowney/merged-results
What is the current bug behavior?
Pipeline for merged results runs and when passes, the merge is immediate. A second pipeline running while a first is running produces the same result and master ends up red/broken.
What is the expected correct behavior?
If merge trains are enabled, the merge request should be added to the train with git push option merge_request.merge_when_pipeline_succeeds.
Relevant logs and/or screenshots
Output of checks
Results of GitLab environment info
Expand for output related to GitLab environment info
(For installations with omnibus-gitlab package run and paste the output of: `sudo gitlab-rake gitlab:env:info`) (For installations from source run and paste the output of: `sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)
Results of GitLab application Check
Expand for output related to the GitLab application check
(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)(we will only investigate if the tests are passing)