After removing 103 false positives, this leaves 4 actually broken tests, showing two failure modes for mail links:
* 'mail without mailto' formatting shortcut in common_linkify didn't get the 'title' attribute added with the other URLs
* links including mailto: protocol are being incorrectly expanded to http: protocol in the long URL
Canon urls that have a protocol followed by a host (and no path) automatcally get a trailing slash by the canon function - make the unit test match that