Merge Request blocked due to non-existent Pipeline

Summary

When a Merge Request requires a successful Pipeline, it is blocked when no Pipeline is available for this branch (e.g. Pipeline is only enabled for main).

Steps to reproduce

  1. Create a project with the following .gitlab-ci.yml:
image: alpine:3
snapshot:
  stage: build
  rules:
    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH      # Pipeline disabled on all branches except main
  script:
    - echo "Hello, World"

  1. Go to project settings > Merge Requests and set "Pipelines must succeed":

    grafik.png

  2. Create a new branch with changes and a Merge Request.

Example Project

https://gitlab.com/luuz/blocked-pipeline-test/

What is the current bug behavior?

The Merge Request is blocked due to the Pipeline, as you can see here: luuz/blocked-pipeline-test!1

grafik.pnggrafik.png

There actually is no Pipeline.

What is the expected correct behavior?

The Merge Request should not be blocked.

Relevant logs and/or screenshots

See screenshots above.

This problem happens on gitlab.com and I verified it on two different self-hosted instances.

Possible fixes

Disable "Pipelines must succeed".