TortoiseHg still uses (the modernized) py2exe packaging, but the build was
failing since py2exe.Distribution was removed.
One thing to note is that later in this module, there's a hack to include
distutils when building from a virtualenv. While import distutils works in
hg debugshell when built with py2, it doesn't work in py3. I'm not sure why-
I don't see it in library.zip either. It doesn't seem to break anything