Summary: Ref T9952. See discussion there. This change is primarily aimed at letting me build a typeahead of branches in a repository so that we can land to arbitrary branches a few diffs from now.
Test Plan:
- Ran migrations.
- Verified database populated properly with PHIDs (`SELECT * FROM repository_refcursor;`).
- Ran `bin/repository update`.
- Viewed a Git repository in Diffusion.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T9952
Differential Revision: https://secure.phabricator.com/D14731
