It accepts these hilarities with or without my original patch applied, so it's no worse than it is before.  I'm not volunteering for making it more restrictive.

public void testRelativeURL() {
  new URIish("http://../example.com/bar.git");
  new URIish("http://example..com/bar.git");
  new URIish("http://example.com/../bar.git");
  new URIish("http://example.com/foo/../bar.git");
}