`linkcheck` logic suggests that SSL errors were originally expected to
be ignored.
Blaming the corresponding lines point to issue #3008: linkcheck to
website with self-signed certificates. That issue was fixed by commit
4c7bec6460, which ignored SSL errors.
Probably because back then, users could not specify a CA bundle.
A broken SSL certificate is a real issue, it should not be ignored.
Users wishing to ignore issues for a specific link can use the
`linkcheck_ignore` option.
The current behavior is to report the site as broken, keep it.
