Comment 1 for bug 1673638

I looked at the inheritance of swift3's ErrorResponse [1] and the implementation of swob's HTTPException [2] - I think we can do better than just log the str of the exception in swift3 [3]

1. https://github.com/openstack/swift3/blob/cd094eea4a0da214d11b67ee6371629379afee1f/swift3/response.py#L154
2. https://github.com/openstack/swift/blob/31ccc2740a6c50742f8878fd4816d74c2c1849b0/swift/common/swob.py#L1384
3. https://github.com/openstack/swift3/blob/cd094eea4a0da214d11b67ee6371629379afee1f/swift3/middleware.py#L85