runtime problems with the dev version

When trying to run the latest Dolfin dev, I get the error message

=================== *snip* ===================
Traceback (most recent call last):
  File "poisson.py", line 17, in <module>
    rhs = project(Constant(1.0), V)
  File "/usr/local/lib/python2.7/dist-packages/dolfin/fem/projection.py", line 104, in project
    form_compiler_parameters=form_compiler_parameters)
  File "/usr/local/lib/python2.7/dist-packages/dolfin/fem/assembling.py", line 259, in assemble_system
    subdomains, form_compiler_parameters)
  File "/usr/local/lib/python2.7/dist-packages/dolfin/fem/form.py", line 74, in __init__
    function_spaces)
  File "/usr/local/lib/python2.7/dist-packages/dolfin/fem/form.py", line 108, in _extract_function_spaces
    r = compiled_form.rank()
  File "/usr/local/lib/python2.7/dist-packages/ufc/ufc.py", line 262, in rank
    def rank(self): return _ufc.form_rank(self)
TypeError: in method 'form_rank', argument 1 of type 'ufc::form const *'
=================== *snip* ===================

This is with the latest UFC dev.
Any idea what could be going wrong?