Totally agree with the migrations (we should raise an issue with South) and certainly with venv and build - not our code.
Not sure we should ignore tests.
I was actually asking more about the ignores (and clearly used the wrong word) - E201,E202 etc. I remember Rob saying we might be over-ignoring on backdrop - I've certainly had a few annoyances where my syntastic has flagged up stuff in backdrop - PITA. I'll take a quick look into those categories and see if they make sense