Bug fix: --user-filter and config invocation default precedence

[bhunut-adobe]

When specify --user-filter manually via cmd line. The value does not set in console output.

When specifying --user-filter and invocation default. --user-filter does not override with arg value instead it listed config file value.

#379

[vossen-adobe]

Nice! Can we get the same behavior using the following?

username_filter_pattern = options['user_filter'] = self.args['user_filter'] or options['user_filter']

[adorton-adobe]

@janssenda-adobe I like the idea, but self.args['user_filter'] will evaluate to False if it set to certain non-None values such as 0, [] or "" (empty string). I think we're safer going with the explicit check that it isn't None. We could do a one-liner in the form Y if X else Z but I think it's clearer to leave it as it is.