Prevent exceptions when adding repositories via conduit.
Summary: Simple change to stop exceptions from being thrown based on the diff in D4146.
Test Plan: arc call-conduit repository.create
Reviewers: epriestley, btrahan
Reviewed By: btrahan
CC: vrana, aran, Korvin
Maniphest Tasks: T2268
Differential Revision: https://secure.phabricator.com/D4342