Update Yahoo ruleset for new SSL support
Opera 20 comes with a few un-editable default search engines. Among them, http://search.yahoo.com/search?ei=UTF-8&fr=opera2&p=…
The HTTPS-Everywhere extension doesn't work for this, even with the experimental setting enabled.
PS: www.eff.org/https-everywhere/atlas/domains/yahoo.com.html mentions search.yahoo.com, but apparently it's not enabled.