setup: configure py2exe config via environment variables The Inno Setup and WiX installers ship a different set of packages with py2exe builds. And there are multiple WiX installer variants (e.g. TortoiseHG). Since there are multiple variants of py2exe configs and they can be defined by entities not in our repository, let's provide a mechanism for setup.py to supplement behavior via environment variables. This is slighly less hacky than a setup.cfg file IMO since the caller doesn't need to worry about mutating global state of the source directory. Differential Revision: https://phab.mercurial-scm.org/D6092

packaging: extract py2exe functionality to own module py2exe builds are shared between Inno Setup and WIX. We'll want the logic for performing py2exe builds to be reusable across the code for both installers. This commit extracts the py2exe-specific functionality into its own module. There's definitely room to customize things further. This will be done in future commits, as necessary. (I'm not even sure what customizations WIX will require yet. Presumably a lot.) Differential Revision: https://phab.mercurial-scm.org/D6091

packaging: extract python exe info to own function This is generic functionality. We'll need it for WIX. As part of the port, we expose the full version and return the data as a dict. Differential Revision: https://phab.mercurial-scm.org/D6090