When executing a submodule, there's a SystemError in 3.3 where we used to receive a ValueError.

mkdir marsu
touch marsu/__init__.py
echo "from .houba import bi" >> marsu/pilami.py

./python marsu/pilami.py

Traceback (most recent call last):
  File "marsu/pilami.py", line 2, in <module>
    from .houba import bi
SystemError: Parent module '' not loaded, cannot perform relative import


In Python 3.2 (or Python 2.7):

./python3.2 marsu/pilami.py

Traceback (most recent call last):
  File "marsu/pilami.py", line 2, in <module>
    from .houba import bi
ValueError: Attempted relative import in non-package