python-cffi and ruby test suites fail in out-of-tree builds

[David Bremner]

Floris Bruynooghe <flub at devork.be> writes:
>
> I checked out the python one, and maybe that's not too hard.  The
> following patch made this work for both in tree and out of tree (on top
> of your other patch):
>
> modified   test/T391-python-cffi.sh
> @@ -8,7 +8,7 @@ fi
>  
>  
>  test_begin_subtest "python cffi tests"
> -pytest_dir=$NOTMUCH_SRCDIR/bindings/python-cffi/build/stage
> +pytest_dir=$NOTMUCH_BUILDDIR/bindings/python-cffi/build/stage
>  printf "[pytest]\nminversion = 3.0\naddopts = -ra\n" > $pytest_dir/pytest.ini
>  test_expect_success "(cd $pytest_dir && ${NOTMUCH_PYTHON} -m pytest --log-file=$TMP_DIRECTORY/test.output)"
>  test_done
>

I smooshed this into id:20200522010359.715688-1-dkg at fifthhorseman.net
and pushed to master.