Too many string-related errors

[GoldsteinE]

There is a lot strings like

self._log.error("Some debug message with %s", value)

I only care about value present in log message (if I care at all), not about log message format. It would be redundant to make assertions about whole log message. So, when mutmut changes this to

self._log.error("XXSome debug message with %sXX", value)

tests doesn't fail. And shouldn't.

I propose adding option not to mutate strings with len() < threshold, because it's possibly human-readable messages which shouldn't be tested.

[GoldsteinE]

And it would be cool to have ability to completely exclude all calls of specific function (e. g. self._log.debug()) from mutation

[boxed]

Yes, we're discussing this and related issues in #47

[boxed]

Closing this in favor of #47