Adds testcase for user_is_back.
Adds testcase for user_is_back.

lukasjuhrich/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,lukasjuhrich/pycroft