attempt to fix fragile spec

This was failing in rails3 during CI, and I suspect it's because of a
database id happening to match the SIS value

Change-Id: I154ce3d3903077aa52d65875ba32489232c11bef
Reviewed-on: https://gerrit.instructure.com/31854
Reviewed-by: James Williams  <jamesw@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Brian Palmer <brianp@instructure.com>
QA-Review: Brian Palmer <brianp@instructure.com>