fix Mailer#create_message spec failures
fix Mailer#create_message spec failures

and probably Mailer#create_message also

Change-Id: I1ff9225e87a790e9929d74c27bc10a3b45740481
Reviewed-on: https://gerrit.instructure.com/64922
Reviewed-by: Matthew Wheeler <ce71fbafda91d6c8f12582e1837687d5fe592dd9@instructure.com>
Tested-by: Jenkins
Reviewed-by: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Product-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
QA-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
Reviewed-by: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
Product-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>
QA-Review: James Williams  <3a5f4ed991dbfa5c9ef76ad729d240ca12f62180@instructure.com>

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