BUG: fix signed zero behavior in npy_divmod

Previously when doing floor division numpy would sometimes return an incorrect
signed zero. For example:

>>> np.zeros(10)//1
array([-0., -0., -0., -0., -0., -0., -0., -0., -0., -0.])

>>> np.remainder(-1.0,1.0)
-0.0

The reason for this is that whenever div or mod were zero the code was using
the following to pick the sign of zero:

floordiv = (a / b > 0) ? 0.0@c@ : -0.0@c@;

This commit updates these lines to instead use the copysign function which is
how cpython does floor division.

Fixes #12841.

0 files changed, 0 insertions, 0 deletions