Fixing p5p's SIG{__WARN__} vs PL_warnhook for Coro

[Kent Fredric]

A few people are trying to fix the PL_warnhook vs $SIG{__WARN__} issue
which Coro hit, but we're unable to find a reliable test for Coro
which will let us know when we've actually fixed it to Coro's
satisfaction.

Is there any light you can shed on this issue?

Ideally this test ought to fail on 4.34 and pass on 4.35, on any perl pre 5.22

Thanks.

-- 
Kent

KENTNL - https://metacpan.org/author/KENTNL