With flake8's other warnings this doesn't make much sense since
indentation accoding to https://hg.python.org/peps/rev/3857909d7956
does not work. It triggers

- 'W503 line break before binary operator'
- 'E129 visually indented line with same indent as next logical line'

If one want to align the operators one hits
- 'E127 continuation line over-indented for visual indent'

So let's leave things as is for the moment.