How to set commit status for Pull Request made from the fork

[IlyaFinkelshteyn]

We in AppVeyor CI recently implemented support for BitBucket PR builds. One of remained issues is that we cannot understand how to setup build status if PR created from the repo fork.

E.g. head (source) repo is in the different user space than base (target) repo.

However this considered a valid scenario for bot private and public repositories so it should be some way to set a status for those Pull Requests.

We tried the following API calls:

/repositories/{BASE_username}/{BASE_repo_slug}/commit/{HEAD_commit_id}/statuses/build -- this call returns 404 and it is understandable as HEAD_commit_id does not exist in the target (base) repository.

/repositories/{HEAD_username}/{HEAD_repo_slug}/commit/{HEAD_commit_id}/statuses/build successfully sets status at the head (source) repository (provided our CI service has enough permissions in that repository), but does not affect status of PR in the target (base) repo.