raven.contrib.celery.register_logger_signal ignores subclasses of SentryHandler

[mpistrang]

raven.contrib.celery.register_logger_signal attempts to find an existing handler to add a CeleryFilter to. It only considers existing handlers that are of type: raven.handlers.logging.SentryHandler. This means that if a subclass of this handler is found (such as raven.contrib.django.handlers.SentryHandler) the existing handler is ignored and a brand new handler with default settings is added, resulting in two potentially duplicate handlers.

The fix for this would be to change the type check here to an isinstance check.

I'm interested in submitting a PR for this with tests, if this change is considered appropriate.

Here is the skeleton of a test that would help cover this:

def test_subclassed_handler_updated(self):
    client = InMemoryClient()
    register_logger_signal(client)

    class CustomHandler(SentryHandler):
        pass

    root = logging.getLogger()
    handler = CustomHandler(client)
    root.addHandler(handler)

    celery.signals.after_setup_logger.send(
        sender=None, logger=root,
        loglevel=logging.WARNING, logfile=None,
        format=u'', colorize=False,
    )

    assert len(root.handlers) == 1

    handler = root.handlers[0]
    assert isinstance(handler, CustomHandler)

    assert len(handler.filters) == 1

    _filter = handler.filters[0]
    assert isinstance(_filter, CeleryFilter)