reckless: fix installation from local directories with subpaths

This could previously copy the parent directory of a plugin
into the installed reckless directory, which was unnecessary.

tests/test_reckless.py

@@ -231,7 +231,6 @@ def test_poetry_install(node_factory):
 
 
 @unittest.skipIf(VALGRIND, "virtual environment triggers memleak detection")
-@unittest.skip("Broken")
 def test_local_dir_install(node_factory):
     """Test search and install from local directory source."""
     n = get_reckless_node(node_factory)