Nick Coghlan <report@bugs.python.org> writes:

> Regarding "__reduce__", other readers will have the same question Éric
> did, so that point should definitely go in a comment after the
> "__reduce_ex__" check.

I just sat down to review this issue, and, looking at test_copy3.patch,
isn't there already a comment next to each __reduce_ex__ check that
reminds the reader that object.__reduce_ex__ will itself call
__reduce__?  Does the comment just need to be more elaborate or
something?

Finally, Éric wants me to replace this:

>         self.assertTrue(issubclass(copy.Error, Exception))

with self.assertIsInstance().  But surely the question is not whether
copy.Error is an *instance* of Exception?  They are both instances of
*type*, right?  What I would need is something like assertIsSubclass or
assertInheritsFrom, neither of which exists.

So I think that test_copy3.patch already includes all of the valid
improvements on the table; if I'm missing one, just point it out and
I'll fix it!