False positive and false negative results for H904

[Gábor Antal]

The H904 rule is poorly regex implemented [0], which causes false positive and false negative results too.

False positive: the rule shoots on the codes, however they should not (live example at [1]):

    LOG = logging.getLogger(__name__)

    def lowerize(st):
        return st.lower()

    def foo(random_string):
        LOG.error("%s is bad" % random_string) # True positive
        LOG.error(lowerize("%s is good" % random_string)) # False positive

False negative: the rule should shoot on the code, but it does not (live example at [2]):

    logger = logging.getLogger(__name__)

    def lowerize(st):
        return st.lower()

    def foo(random_string):
        logger.error("%s is bad" % random_string) # False negative

[0]: https://review.openstack.org/#/c/343824/2/hacking/checks/other.py
[1]: https://github.com/openstack/trove/blob/master/trove/common/auth.py#L64
[2]: https://github.com/openstack/trove/blob/master/trove/db/sqlalchemy/migration.py#L62