Show the position of a merge request in a Merge Train

Problem to solve

In order to let users know where a merge request is in a merge train, we need to inform in the UI of a merge request position once it enters the merge train.

Acceptance Criteria

  • Given no previous merge train exists: If the pipeline succeeds, the merge request will automatically be merged. The merge request will be placed in position 1 in the Merge train and a helper text is added under the pipeline block.
  • Given a merge train exists: The new pipeline won't start until the previous one finishes. If the pipeline succeeds, the merge request will automatically be merged. The merge request will be placed in position n in the Merge Train and a helper text is added under the pipeline block.

Screen_Shot_2019-06-05_at_18.58.26

Full prototype can be see on https://gitlab.com/gitlab-org/gitlab-ee/issues/9186