Add a missing migration

Summary: This migration script is required for D9999, which has already landed.

Test Plan: Ran ./bin/storage upgrade and can log in again.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D10010