Apply_lifting in the context of a block system

Lifting on 0.9.0 is part of assemble_vector_block, see the lines:

thus, by modifying the inputs to x0 and alpha in: dolfinx/python/dolfinx/fem/petsc.py at v0.9.0.post1 · FEniCS/dolfinx · GitHub
you should be able to do what you want.

As already stated, this is fully revamped on the main branch.