Description As seen in https://travis-ci.org/astropy/astropy/jobs/455917279 , from skimage.measure import block_reduce caused ImportError when used with numpy dev. from skimage.measure import block...

_validate_lengths replaced in numpy 1.16 leading to ImportError exception in scikit-image less than 0.14.2 · Issue #3551 · scikit-image/scikit-image