Summary: Ref T2222. This is obsolete and no longer used. We could deduce it from transactions or commits in modern Phabricator if we wanted it. We may implement a more general mechanism for T4434.
Test Plan: `grep`
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T2222
Differential Revision: https://secure.phabricator.com/D8330
