Try to automatically fix files with mixed tabs about python-driver

[abeaumont]

Is the source code valid or invalid? If it's the former why does the AST module fail? If it's the latter I think it should fail, we shouldn't be correcting invalid code.

[juanjux]

Is invalid in Python 2/3 and valid in Python 1 (Python2 produces a SyntaxError and Python3 a TabError). I don't know how people run that code actually if they're using a version of Python from the last decade.

AFAIK I got the impression from some early meetings that we should try to parse code with errors if we can get something out of it and in this case it would be easy; I don't know if that's still an objective.

In any case I was very tempted to mark this as feature but I would prefer to ear some opinions before doing that again.

[abeaumont]

We have decided not to support Python 1. Handling this would be in the scope of the user