Nice sleuthing! I was at first surprised this file gets checked at all, since it is not documented, but only then realized that pytest collection and sphinx documentation are of course completely unrelated. It still seems odd, however, that a doctest would run on something that is not actually defined in the module. But checking, I see that there is just no way to see where the ufunc is actually defined.

So, am happy to go with this - though do please add a comment!

Also, I guess if we will eventually use the new pytest-doctestplus functionality in LTS, this should be backported?

p.s. Longer term, it might more sense to move all those additions to a function, as is done for scipy.py, but that can be in another PR...

Oh wait... My PR is not supposed to be merge. Never mind... 🤪