spec: Fixed the verify_logout method.

Change-Id: Ia84cf464d9c91dead4401db26553121cfe4f2c95
Reviewed-on: https://gerrit.instructure.com/44243
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: Kyle Rosenbaum <kyler@instructure.com>
Reviewed-by: Kyle Rosenbaum <kyler@instructure.com>
QA-Review: Kyle Rosenbaum <kyler@instructure.com>