Version 2.0.1-5 of libopenmpi-dev contains a patch which should fix the FTBFS of mpi4py (2.0.0-2). The broken mpi4py build is holding up a load of other packages that need rebuilding in the openmpi transition. Can mpi4py be given back to the needs-build state?
gb mpi4py_2.0.0-2+b1 . ANY