So I went to
https://blog.wikimedia.org.uk/2015/07/welcoming-lucy-crompton-reid-as-new-c…
and Firefox 41.0.1 complains about the SSL cert:
blog.wikimedia.org.uk uses an invalid security certificate. The
certificate is not trusted because the issuer certificate is unknown.
The server might not be sending the appropriate intermediate
certificates. An additional root certificate may need to be imported.
(Error code: sec_error_unknown_issuer)
Works fine in Chromium 45.0.2454.101.
- d.