ignore irrelevant pylint warning

The pylint warning below was added in pylint 1.4.

> [W1202]:logging-format-interpolation: Use % formatting in logging
> functions but pass the % parameters as arguments

However, it's not really applicable to git-fat since we don't use old
style formatting (which is all the logging module supports)

More info:
http://stackoverflow.com/questions/12843099/python-logging-typeerror-not-all-arguments-converted-during-string-formatting