At the very least this is a documentation bug. By reading the std docs
on the logging module [1] one gets the impression that if a log record
gets to a certain logger, even if percolated from more specific loggers,
then the filters to that logger should be involved and even get the
chance to change the log record.

[1] http://docs.python.org/library/logging.html

This is reinforced by the documentation and the implementation of the
logging.Filter class, which is supposed to filter-out messages of more
specific loggers, but which would never actually filter out anything if
applied to a Logger of the same "name" (as opposed to a Handler, since
filter handlers do get called for log records of more specific loggers).