If someone uses the bitbucket web interface to edit a file, create their own fork, and create a PR with the edit, that fork may not be shared automatically with the owners of the upstream repo.
The upstream owners can still view the PR itself, and optionally merge it in the bitbucket web interface, but since the fork is not shared with the upstream owners, they cannot locally add the fork as a remote to pull from, in the event that they want to tweak the change before merging.
Is there something I'm missing here, or do all PR-submitters need to be trained to share their repo with the upstream maintainers?