Once we complete the 0.13 client Peter is working on we need to rebase to 0.13.2 making the changes in a sane way, smaller self contained changes with the final versions.We have been going through the AcceptBlock/CheckBlock code to look for additional rules there. We picked some up from another codebase which we need to remove.We already know how to resolve this, overlay XBC on to Bitcoin 0.7.2 then we can see what AcceptBlock/CheckBlock rules apply to us only. We do not want to accidently fork!
As to when new client will be ready for release the short answer August without factoring in Murphy's law.
We expect to rebase after Peter gets back from holiday, even if we managed to do it before he would not want the client released while away in case we did get an unexpected fork.He will need to be available during the process.