I find fine planning to have a "normal", small release. But if the code
development lead to eg. a parser rewrite, that's fine too. It can get
in, or reverted for the branch if too close to the brach point.
As far as it gets reviewed in time, it shouldn't be a problem. (We are
going to get everything timely reviewed™ this time, right? ;) However,
if it gets unreviewed three months, with furhter changes dependant of
it, and is only looked at two weeks before the branching date (and
obviously finding issues), then such rewrite becomes a big problem.