py2exe executables do not maintain the parent's
environment for childprocesses.
py2exe initialize its sys.path via a PYTHONPATH env
variable that is set before Py_Initialize() is called.
Other env vars are changed as well.
This patch uses a different approach to set the initial
sys.path before Py_Initialize() is called. Env vars
are not used at all.
Kind of a hack, we let Py_GetPath() calculate the
default path, and overwrite it then. This assumes the
Py_GetPath() returns a pointer to mutable memory.
It has to be checked in Python's source code if this
assumption is really correct in all cases.