This morning I talked to Roan about his thoughts about branching 1.18 now that 1.17beta1 is out. He was in favor of it so I said I would ask Tim what he thought and then (assuming Tim was OK with it) branch it.
So, after asking Tim for his POV and getting his OK, I went ahead and created http://svn.wikimedia.org/mediawiki/branches/REL1_18/ to hold phase3.
I recognize that I will have to be prepared to merge fixes that fix bugs in 1.17 with the branch I've just created — but I'm anxious to get the 1.18 release on the road NOW.
Along with this, I'm going to be coordinating code review with the developers and making sure we're aware of our respective areas of responsibility. I think we're agreed that the keeping CR current is necessary to have a timely 1.18 release and avoid delays.
Happy hacking!
Mark.