I'm CCing the LAMMPS mail list, b/c this is really a LAMMPS tool
you are running. The env variable setting is just for Python to find
the Python files you are importing into the dump2cfg.py tool.
Try this first: put the *.py files in tools/python/pizza into the same
dir as dump2cfg.py. Then run from that dir on some dump file
you have. That should just work. Then if you set LAMMPS_PYTHON_TOOLS
to the lammps/tools/pizza dir, that should also work, even if
you delete the pizza dir files from the lammps/tools dir.
Steve