[covtype.py](https://lgtm.com/projects/g/scikit-learn/scikit-learn/snapshot/1a981e87ba6f8d66ecfd6940184836446ded3f4c/files/sklearn/datasets/covtype.py#L92) and [rcv1.py](https://lgtm.com/projects/g/scikit-learn/scikit-learn/snapshot/1a981e87ba6f8d66ecfd6940184836446ded3f4c/files/sklearn/datasets/rcv1.py#L117) depend on Python3 standard library parameters when `download_if_missing` is used. We promise Python 2 support. H/T: lgtm.com