This is done by adding a PyTargetAdd function, which builds the target into a Python ABI-specific temporary directory, allowing multiple Python versions to be built into the same built dir side-by-side. This could greatly speed up buildbot builds.
It also paves the way for building multiple Python versions in the same makepanda call / installer by changing PyTargetAdd to add one target per enabled Python version.
This makes it possible to run pytest in the root directory. It also lets us store metadata such as the current version number, preventing us from having this in several different places, and allowing us to phase out parsing dtool/PandaVersion.pp.
rdb