Assuming the next 0.21 release happens around or after April 2019, the oldest Ubuntu LTS at that point will be 16.04 LTS, which includes,
(checked in a Docker image, not sure where to find the official information)
so we could probably make these our minimum requirements for 0.21.
Making so would for instance allow to implement https://github.com/scikit-learn/scikit-learn/issues/11638
Even assuming there is agreement on this subject, we should probably wait for 0.20.1, at least, before doing anything about it. Eventually this would involve,
utils.fixes
that are no longer needed. I would also be in favor of bumping dependencies for scikit-learn 0.21 to those matching ubuntu 16.04 LTS so as to be able to implement what is described in #11638.
+1 on bumping and +1 on waiting for 0.20.1
From #12718
We should also consider the version of matplotlib and scikit-image
It's 1.5.1 for matplotlib (https://packages.ubuntu.com/xenial/python3-matplotlib) and 0.10.1 for scikit-image (https://packages.ubuntu.com/xenial/python3-skimage).
Most helpful comment
I would also be in favor of bumping dependencies for scikit-learn 0.21 to those matching ubuntu 16.04 LTS so as to be able to implement what is described in #11638.