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.