Pull requests plugin: allow manually triggering build outside of organization

We're using the pull requests plugin to restrict builds to members of our organization. We occasionally get PRs from external contributors and while we don't want to build these on our servers automatically, eventually we do want to verify the PR successfully builds before merging it in. But I can't see a way to trigger a build for them manually after we've reviewed them. Is this possible? 

I did come across https://youtrack.jetbrains.com/issue/TW-58062 which suggests that it will be in a future version but we'd love to have a clean way of doing it now.