isl_test_python.py: stop raising strings
isl_test_python.py: stop raising strings

This was deprecated in Python 2.5.

Requested-by: Matthias Klose <91dc2f4761949af6331263735e0928d901fc6619@canonical.com>
Signed-off-by: Sven Verdoolaege <235c10dd23b819f81cdc9756a251746bc184cab6@gmail.com>

Meinersbur/isl,Meinersbur/isl,Meinersbur/isl,Meinersbur/isl