fix sis_source_id setting with new roles

Change-Id: I4beb68a93f6eb4a613e63d12ec79dbca179083ed
Reviewed-on: https://gerrit.instructure.com/44447
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
QA-Review: James Williams  <jamesw@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>