Fix flake8 fail on py3 syntax while it run from py2 tox
Fix flake8 fail on py3 syntax while it run from py2 tox

telstra/open-kilda,jonvestal/open-kilda,telstra/open-kilda,telstra/open-kilda,jonvestal/open-kilda,telstra/open-kilda,jonvestal/open-kilda,jonvestal/open-kilda,telstra/open-kilda,jonvestal/open-kilda,telstra/open-kilda,telstra/open-kilda