Audit - another partial fix to commit re-parsing bug

Summary: Ref T6350. We build $sql based on whose subscribed. If no one is subscribed, then we have no query to run.

Test Plan: observed one error disappearing from my daemon log. Also, more doing it live.

Reviewers: epriestley, chad

Reviewed By: chad

Subscribers: Korvin, epriestley

Maniphest Tasks: T6350

Differential Revision: https://secure.phabricator.com/D10731