Description
I'm not sure why this never came up for me before. I did recently reinstall Cygwin, and maybe had forgotten that I long ago symlinked locale.h to xlocale.h. Another possibility is that the version of Cygwin I was using didn't define strtold_l, which is the only case in which Numpy looks for xlocale.h.
Upstream report at numpy/numpy#8367
Upstream: Fixed upstream, in a later stable release.
Component: porting: Cygwin
Author: Erik Bray
Branch: bbe65d1
Reviewer: Travis Scrimshaw
Issue created by migration from https://trac.sagemath.org/ticket/22049