I have a branch which fixes this. I will be putting in a pull request imminently. In the meantime, if you upgrade PETSc to current master, you will need to use my petsc4py branch. This can be installed (system-wide) with:

sudo pip install -U --no-deps  git+https://bitbucket.org/David_Ham/petsc4py.git@DMDASetDim_interface_change#egg=petsc4py

I will let you know once normal service resumes.

David

Dr David Ham
Departments of Mathematics and Computing
Imperial College London

http://www.imperial.ac.uk/people/david.ham