FIX W504 warning: Line break occurred after a binary operator
    
    After upgrading C3I Jenkins slave pod from Fedora 28 to 29,
    C3I pipeline builds for waiverdb fails with a Flake8 warning:
    [W504 line break after binary operator][2].
    
    This happens because of a [updated PEP 8 rule][1], which
    recommends that line breaks should occur before the binary operator
    because it keeps all operators aligned.
    However [both W503 and W504 are enforced when all warnings are configured][3].
    
    This pull-request eliminates the warning by following the new rule and ignoring W503.
    
    [1]: https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator
    [2]: https://lintlyci.github.io/Flake8Rules/rules/W504.html
    [3]: https://gitlab.com/pycqa/flake8/issues/463