rsync: filter() method + delete=True leads to unexpected results

I'm using an RSync subclass that implements filter() to ignore some parts of a large tree, specifically things where the remote side has a local version like a virtualenv that should not be touched at all, however, it currently always deletes the remote version ...

I'd be happy to improve the code but need to know whether in general filter()=False + delete=True would expect a filtered item to be removed or left alone on the remote side ... my personal favorite would be to have it ignore the deletions on the remote side and eventually adding a delete_filtered option. This would be in sync with the way regular rsync works.

No files or tests are named. Start by locating the RSync filter() and delete=True handling, then review existing synchronization tests and the documented behavior of regular rsync. Done means the expected treatment of filtered remote items is decided and covered by regression tests.