bug#16791: w3m fails to do any SSL certificate checking

[Mark H Weaver]

In Guix, neither w3m nor emacs-w3m warn me when I visit an https URL
that uses a server certificate that is both self-signed and expired.
To make matters worse, if I ask for page information (with the '=' key),
it tells me that the certificate is valid.

On Debian, both w3m and emacs-w3m inform me when an SSL certificate is
invalid in some way, e.g. if it's expired or not signed by a certificate
authority in my trust store.

      Mark