R1:519bec3e6f36

Make searching by tags work in Phriction

Summary: Fixes T12860. Some joins were being dropped because we didn't call `parent::...`

Test Plan:
- Tagged a document.
- Searched for documents with that tag.
- Before change: got all documents.
- After change: got only tagged documents.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12860

Differential Revision: https://secure.phabricator.com/D18145