Bugfix for D7596
Summary: Fixed a small bug that caused the catch-all commit to purge previously added symbols in that session.
Test Plan: Re-ran the script, observed corrected behavior.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley
CC: Korvin, epriestley, aran
Maniphest Tasks: T4117
Differential Revision: https://secure.phabricator.com/D7597