PositionalArgumentsFormatter does not remove empty list of args

[keis]

PositionalArgumentsFormatter with remove_positional_args=True is supposed to remove the positional_args from the event dict. However this only happens when positional_args is truthy which is not the case for the empty list. _proxy_to_logger takes care not to add these to begin with but you can still hit this unexpected behaviour if setting this attribute somewhere else. In my case using a stdlib logging handler to funnel messages into structlog.

[hynek]

This should be fixed now. Sorry for the lack of feedback.