This is about an artifact transferring failure, not about a problem with the pull request itself.
I can’t just click on ‘rebuild’ button to resolve this unintended behavior.
I suppose the authors of the original repository I made the PR for don’t want even watch at any PR if there was a build error.
So, what can I do as a contributor without creating a new pull request?
As a contributor, you can create an empty commit with git commit --allow-empty and push it to trigger a rebuild. PRs intentionally disallow build restarting to prevent contributors from smuggling unreliable code in.