quote from http://docs.python.org/3/library/imp.html#imp.find_module:

"...on some systems some other places are looked in as well (on Windows, it looks in the registry which may point to a specific file)."

I actually didn't know the registry key is listed in "using Python on Window" guide until I grepped for PythonCore (which kind of requires to know the key already) - so I'm submitting a patch that cross references find_module docs and using Python on Windows guide.