Here is a pure Python patch that skips any frames that mentions 'importlib' and '_bootstrap' in the filename (it also skips _warnings.warn for easy testing since I didn't implement the C part). The only side-effect is that negative stack levels won't be the same because of the change in line numbers, but in that instance I'm not going to worry about it. It also causes test_venv and test_warnings to fail but I have not looked into why.

And still need a call by Larry as to whether this will go into 3.5.0.