It seems that you’ve mentioned an “undefined Pull Request” without providing any specific details or context about the changes, features, or issues addressed in the Pull Request for the Thanos project (thanos-io/thanos). Unfortunately, without this information, I can’t create a meaningful summary.

If you could provide details such as the purpose of the Pull Request, key changes, any relevant issues it addresses, or particular areas of the codebase that it affects, I would be happy to help you write a summary tailored for an advanced developer.