Strange JIT caching behaviour

[Harish Narayanan]

When I run the following script,

from dolfin import *
parameters["form_compiler"]["name"] = "sfc"

mesh = UnitCube(3, 3, 3)

V = VectorFunctionSpace(mesh, "Lagrange", 1)
Q = FunctionSpace(mesh, "Lagrange", 1)

u = Function(V)

for j in range(1, 10):
    term = project(grad(u)[0][1], Q)

I find that sfc attempts to JIT-compile the project term seemingly an arbitrary number of times, and complains 'Possibly overwriting files in existing module directory foobar/sfc_jithash'. This doesn't happen when using ffc as the form compiler.