There is a new version available for ROOT Framework Reproducible: Always Steps to Reproduce: Expected Results: Update to the next available version. There some important updates available. I have done a test where I have been able to compile the new ROOT version by using the ROOT ebuild for 5.26 version with quick and dirty changes (deleting cint7 and geant4 options, and deleting the patches for 5.26). I guess the only change that has to be done is regarding CINT7.
ROOT version 5.28/00 will be released on June 30 2010, so I don't think this developer version is really worth the effort unless someone steps in. I might roll another patch release for 5.26.00 though.
OK! I agree with you. So I will close as WONTFIX.