Dear firedrakers,
with latest Firedrake, you'll require a new UFL + FFC combo.  This is
merging upstream work such that we can start looking at implementing
non-affine geometries.  The UFL update is a reset of master, if you have
a pip install of UFL, please just reinstall as before.  If, however,
you're maintaining a local clone of our UFL repository you'll need to do
the following to update to latest master.
** Note **
The following sequence of instructions discards any local changes you
have on the master branch.  You'll need to move those to a new branch
before carrying on.
$ git checkout master
$ git fetch
$ git reset --hard origin/master
Please do email if something goes amiss.
Cheers,
Lawrence