If 'noqa' is specified all hacking checks are disabled.
It is better to ignore specific rules explicitly rather than
ignoring all. The recent flake8 supports this [1].
[1] http://flake8.pycqa.org/en/latest/user/ignoring-errors.html
Change-Id: I74246adb4d1d2613c2703cf519428b64d00e59bb