As reported in #11166 (comment):

This has broken CircleCI on master, which is trying, if I understand correctly, to load pickles which reference sklearn.externals.joblib.numpy_pickle, resulting in an ImportError.

Firstly, I presume to fix Circle, we just need to clear a cache somewhere (but I've not worked out where).

Secondly, are we unnecessarily breaking pickles from previous versions? Should we see if we can find a way to make this function importable when loading a joblib pickle?

See subsequent discussion there.

This issue is just to make sure we have some resolution before 0.20 release