Comments break assertion in ruamel

Summary

When having a comment in a (>), there is an assertion that breaks during tracking.

Steps to reproduce

Have an element like that:

config:
  build-commands:
    (>):
    # Comment
    - list

Track it, and make sure that one source plugin will find a new ref.

What is the current bug behavior?

Assertion breaks in ruamel.yaml.

What is the expected correct behavior?

It should not break.

Relevant logs and/or screenshots

See example of error: https://gitlab.com/freedesktop-sdk/freedesktop-sdk/-/jobs/305566027

Possible fixes

Other relevant information

It happens on 1.4 branch.