I wanted to use gdal_polygonize but I see it's not part of this install. It's a little weird because it's called from the command line as gdal_polygonize.py whereas other commands don't have .py – so perhaps it's an add-on of some kind?

It would be helpful if this came bundled with Postgres so I could avoid managing possibly two different installs of gdal but maybe there was a good reason it was omitted...