Fix data_tests/package_for_test_meson for JAX

.hgignore

@@ -35,6 +35,7 @@ doc/ipynb/*.rst
 **/__cython__/*
 **/__numba__/*
 **/__python__/*
+**/__jax__/*
 
 doc/for_dev/**/*.c
 doc/for_dev/**/*.html

data_tests/package_for_test_meson/README.md

@@ -21,7 +21,7 @@ needed for the editable mode (see
 We can also install with another backend with:
 
 ```sh
-pip install --no-build-isolation --config-settings=setup-args=-Dtransonic-backend=python .
+pip install --no-build-isolation -C setup-args=-Dtransonic-backend=python .
 # or (but does not work here for another reason)
 python -m build --no-isolation -Csetup-args=-Dtransonic-backend=python .
 ```

data_tests/package_for_test_meson/src/package_for_test_meson/for_test__jax__meson.build

@@ -0,0 +1,10 @@
+python_sources = [
+  'bar.py',
+  'foo.py',
+]
+
+py.install_sources(
+  python_sources,
+  pure: false,
+  subdir: 'package_for_test_meson/__jax__',
+)