don't orphan a DB connection in the main passenger thread
don't orphan a DB connection in the main passenger thread

fixes CNVS-37760

Change-Id: I842c0f113f9bbf769eef30f3f7d3d729e1c44d44
Reviewed-on: https://gerrit.instructure.com/118594
Tested-by: Jenkins
Reviewed-by: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

djbender/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,djbender/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms