only swallow exceptions for test shards when migrating
only swallow exceptions for test shards when migrating

not when trying to run specs

Change-Id: I2c13e32df6b1c14ef206cdaca6934589f777b0ef
Reviewed-on: https://gerrit.instructure.com/67431
Tested-by: Jenkins
Reviewed-by: Simon Williams <088e16a1019277b15d58faf0541e11910eb756f6@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

instructure/switchman,instructure/switchman