There are only two instances of this usage in Thicket, both in init.py. Before making the change, we need to determine if this is backward compatible with Blender 2.80 through 2.90 and special case ...

A side-effect of no longer propagating import paths using the PYTHONPATH envvar is that subprocesses don't inherit the paths. This is usually a good thing, but ends up breaking plain calls to python ...