Changed test for shift existance on change email
Changed test for shift existance on change email

Catching DoesNotExist exception spit ERROR logs on test running (when
done with activated logging).
As exception catching additionally might be more expensive than
existance testing and conditional code paths it's changed.

flindenberg/volunteer_planner,pitpalme/volunteer_planner,juliabiro/volunteer_planner,volunteer-planner/volunteer_planner,volunteer-planner/volunteer_planner,pitpalme/volunteer_planner,volunteer-planner/volunteer_planner,slevon/volunteer_planner,jonasrk/volunteer_planner,flindenberg/volunteer_planner,alper/volunteer_planner,christophmeissner/volunteer_planner,MRigal/volunteer_planner,christophmeissner/volunteer_planner,volunteer-planner/volunteer_planner,christophmeissner/volunteer_planner,christophmeissner/volunteer_planner,coders4help/volunteer_planner,juliabiro/volunteer_planner,pitpalme/volunteer_planner,slevon/volunteer_planner,alper/volunteer_planner,jonasrk/volunteer_planner,pitpalme/volunteer_planner,klinger/volunteer_planner,alper/volunteer_planner,juliabiro/volunteer_planner,MRigal/volunteer_planner,slevon/volunteer_planner,flindenberg/volunteer_planner,jonasrk/volunteer_planner,jonasrk/volunteer_planner,klinger/volunteer_planner,slevon/volunteer_planner,klinger/volunteer_planner,coders4help/volunteer_planner,klinger/volunteer_planner,coders4help/volunteer_planner,slevon/volunteer_planner,jonasrk/volunteer_planner,coders4help/volunteer_planner,MRigal/volunteer_planner