Well I spent most of the afternoon trying to get Gnome 2.13.91 (2.14 Beta 2) to build. The first problem was with libxklavier. The version in jhbuild fails to build, I filed this bug but in the meantime replacing with libxklavier2.1 fixes it.
The only other problem is with epiphany which fails to build. It cannot find iso-codes. I actually think the problem is with iso-codes because running in jhbuild shell, it cannot be found. Maybe iso-codes make install is broken.
Anyway tomorrow I will have a go at building jhbuild in chroot (im trying to get a working GnomeLiveCD from using jhbuild). More on that later