Typeslots.inc is listed in the .hgtouch file, so you might be able to work around by running “make touch” before building. I noticed there are other boostrap scripts that require a “python” command via various mechanisms, e.g. Python/makeopcodetargets.py is run via “#! /usr/bin/env python” by default. It would at least be nice to make everything uniform, i.e. always use a /usr/bin/env hashbang, always use $(PYTHON), or always use this smarter external Python command.