Alter the behaviour of W291 (trailing whitespace).
Alter the behaviour of W291 (trailing whitespace).

The previous implementation called out errors in lines which
were only whitespace, such as those matched to their surrounding
indentation level. This meant code formatted to avoid accidentally
terminating class declarations in the Python interpreter threw up
warnings in a PEP8 check.

papaeye/pep8,reinout/pep8,jayvdb/pep8,zevnux/pep8,PyCQA/pep8,MeteorAdminz/pep8,ABaldwinHunter/pep8-clone-classic,fabioz/pep8,asandyz/pep8,fabioz/pep8,pedros/pep8,dpursehouse/pep8,ojengwa/pep8,dpursehouse/pep8,codeclimate/pep8,doismellburning/pep8,pandeesh/pep8,reinout/pep8,jayvdb/pep8,ABaldwinHunter/pep8