[firedrake] Perturbing mesh extrusion at runtime

Hi all, Custom mesh extrusions can be generated by manipulating mesh.coordinates directly. This works fine as long as the coordinates are changed prior to the first solve. After that changing the coordinates has no effect as precomputed mesh properties do not get updated. What do I need to do to force a mesh update? I need to update the extrusion only, not the parent mesh. Can this be done efficiently? Cheers, Tuomas