fix rails 3 shard deserialization into rails 2

Change-Id: I3c93d8ac833ca4c78f6da51f03202eadfa78dea8
Reviewed-on: https://gerrit.instructure.com/37856
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
Product-Review: James Williams  <jamesw@instructure.com>