ensure extensions will work for specs with multiple shards

Change-Id: I4ff6ab571f7995469a89f605386e9f6c49718d19
Reviewed-on: https://gerrit.instructure.com/29677
Reviewed-by: Jon Willesen <jonw@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>