I develop in python since 10+ years. And setting up a virtualenv only happens when developing patches for 3rd party packages. (due to the other commercial environment that doesn't work with venvs).
And it is a totally miserable experience on Windows, every single time.
As long as you cannot even prove that due to a lacking python code signing infrastructure for packages (wheels can do it, but it is far from wide spread).
And setup.py is a trainwreck, e.g. some packages compile download and compile huge dependencies (e.g. a full Apache httpd...), the default compiler flags may lack all the mandatory security flags (e.g. for using ASLR on python 2.x), or ship their own copy of openssl statically and break your FIPS-140 certification that way...
http://kitcreator.rkeene.org/fossil/wiki?name=KitDLL