Work around for the wrong locale

Summary:
REMARK: This is not a real fix for the problem documented in T24692.
It cures the symptomes, but the underlying problem
(why is the locale becomming wrong?) is not yet identified or fixed.

Signed-off-by: Ralf Floca <r.floca@dkfz-heidelberg.de>

Test Plan: Unit tests

Reviewers: O1 MITK Core, kislinsk

Reviewed By: O1 MITK Core, kislinsk

Maniphest Tasks: T24692

Differential Revision: https://phabricator.mitk.org/D123