The new test should be moved down to rule 3, probably just before the
deprecated addr test, that is, a deprecated addr which is still valid
should be preferred over a detached (or tentative) addr - detached I
will come back to in the next section, but for tentative this means that
if an old addr has become deprecated, and we're in the process of
generating
a new one, but DaD has not completed yet, we keep using the old addr
until the new one is no longer tentative, and then switch (the way your
code is now would also do that - but because the check is much too
violent.)
This is why you might consider this just to be a coding change (with
functional
side effects.)