Philippe Pepiot <philippe.pepiot@logilab.fr> [Mon, 29 Oct 2018 10:09:19 +0100] rev 12354
Stabilize flake8 tests on 3.26 branch
Use basepython=python2 or flake8 installed with python3 will raise "[F821]
undefined name 'buffer'"
Pin flake8 < 3.6 which has new checks that doesn't pass on our current code base.