Since py23 modifies some essential builtins, it's safe to import
everything all the time. At least, that's how it was designed.
It's a bug if importing * breaks some code.
Apparently I need to do that, or the child python process does not see fontTools in the path.
Another workaround woud be to ensure that fontTools is installed, at least in editable or develop mode (via `pip install -e .`). But the way we temporarily extend the PYTHONPATH in run-test.sh is less intrusive.