don't do a query just to convert an id to an object with just an id

Change-Id: Iba0c38881fc37a44391ed7e4882a0ba0e147236c
Reviewed-on: https://gerrit.instructure.com/40480
Reviewed-by: Brian Palmer <brianp@instructure.com>
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>