Quantal is now open for development.
Matthias Klose announce: https://lists.ubuntu.com/archives/ubuntu-devel/2012-April/035152.html
"Quantal is now open for development, with syncs from unstable starting shortly. The development version starts with updated versions of GCC and OpenJDK, some soname changes (boost, hdf5), and some changes with setting the build flags for package builds. We are finally targeting Python3 as the only Python version on the ISO/installation images.
- GCC 4.7 is now the default, introducing some build failures caused by unknown compiler options, and more C++ strictness. Hints how to fix packages can be found at [1]. Bug reports for packages are not yet filed directly in Launchpad, but can be found on the Debian BTS instead [2].
- OpenJDK 7 is now used as the default, replacing OpenJDK 6, introducing some build failures. The build status can be tracked at [3], open issues are tracked at [4].
- Removing build flags exported from dpkg-buildpackage for quantal will get us in sync with Debian. Implications and fixes are discussed on the ubuntu-devel ML [5].
- Python 3 is now again part of a minimal chroot on quantal, and will be the only Python version provided on the ISO/installation images for quantal. Packages which need updates and ports for Python 3 are tracked at [6]
Please check your uploads in a quantal chroot, don't just test in a precise environment. See [7] how to setup such a development chroot."