Summary:
`ReleephRequest`s contain the PHID for a `PhabricatorRepositoryCommit`, and commits have an edge to a `DifferentialRevision`.
Commits are loaded with the `loadOneRelative()` method that loads the commits for every `ReleephRequest` in a `LiskDAOSet`, but the edges are loaded indivdually. A page with N RQs on it makes one DB query for the commits, but N queries for the `TYPE_COMMIT_HAS_DREV` edges.
This diff uses `loadRelativeEdges` instead to load the edges all in one query.
Test Plan: {F42290}
Reviewers: wez, epriestley
Reviewed By: epriestley
CC: epriestley, vrana, aran
Maniphest Tasks: T2714
Differential Revision: https://secure.phabricator.com/D5820
Summary: Migration doesn't delete differential.revisionPHID but maybe it should?
Test Plan: Reparsed commit, ran the migration, deleted differential.revisionPHID, looked at task with attached commit with attached revision.
Reviewers: epriestley, edward
Reviewed By: epriestley
CC: aran, Korvin, AnhNhan
Differential Revision: https://secure.phabricator.com/D5634
