I figured out the python.exe is a dynamically-linked python for use
under systems like ubuntu where the provided distribution is statically
linked. But I had already installed an overriding distribution of
python from sources.
FYI, ubuntu's distribution is this way because for whatever reason it is
configured with --disable-shared. If you (like me) check out python
from sources and configure a version with --enable-shared and install
it, you don't have to use python.exe. Not that I'm anti-python.exe, but
I wanted to know precisely what was different under ubuntu, and it turns
out this is the necessary and sufficient configuration change.