Backend: Trigger job with strategy depend shows green when child pipeline passes with warnings

Update

Our going forward approach will be to implement Backend: Implement strategy: mirror (#431882 - closed), this should resolve the problem and allow users to opt-in this capability without introducing breaking changes

Summary

We trigger a child pipeline with strategy: depend. When the child pipeline completes with passed with warnings, the triggering job is wrongly displayed green when it should show amber. For completeness, when the child pipeline is green or red, the triggering job shows the correct status.

Steps to reproduce

Our pipeline definition is something like this:

generate-config:
  stage: generate
  script:
    # some script here to generate generated.yaml  
  artifacts:
    paths:
      - generated.yaml

child-pipeline:
  stage: build
  trigger:
    include:
      - artifact: generated.yaml
        job: generate-config
    strategy: depend

with some jobs in the child pipeline set to allow failure. When one of those jobs fails, we get

What is the current bug behavior?

The triggering job shows passed, green.

What is the expected correct behavior?

The triggering job should show passed with warnings, the same as the child pipeline. This is because strategy: depend is set.

Results of GitLab environment info

GitLab Enterprise Edition 13.5.3-ee