spec: make import specs less fragile to other data in db

Change-Id: Ibbfc6f525c3d649fe8f0075c82c5d678f9373cd9
Reviewed-on: https://gerrit.instructure.com/29860
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Rob Orton <rob@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>