[aferen@xxxxxxxxxxxx (Andrew C. Feren)]

The short answer is to always specify the full path to the python
.exe and you will stop getting the following error

NMAKE : fatal error U1095: expanded command line ... too long


I had previously asserted that changing from the Cygwin python to the
python from python.org solved the problem.  This is sort of true.

Here is the long matrix of what I found:

In a Cygwin environment
    Assumptions:
        c:\cygwin\bin is the correct path
        c:\cygwin\bin is in the path (ahead of any other Python)
        Cygwin 2.78.2.15 (because that is what I happen to have)

PYTHON=python   
    result ==> NMAKE : fatal error U1045: spawn failed : Invalid argument

PYTHON=python.exe   
    result ==> NMAKE : fatal error U1045: spawn failed : Invalid argument

PYTHON=python2.2
    result ==> NMAKE : fatal error U1095: expanded command line ... too long

PYTHON=python2.2.exe
    result ==> success

PYTHON=c:\cygwin\bin\python2.2.exe
    result ==> success


Using Python 2.2 from python.org
    Assumptions:
        c:\Python22 is the correct path
        c:\Python22 is in the path (ahead of any other Python)

PYTHON=python
    result ==> success

PYTHON=python.exe
    result ==> success

PYTHON=c:\Python22\python.exe
    result ==> success


It appears that somehow this is realated to the python distribution
the path length specified is not the issue since clearly
"c:\cygwin\bin\python2.2.exe" is the longest of the choices and this
works.

I don't pretend to understand why this behaves the way it does, but I
can definately reproduce this behavior consistently.

-- 
-Andrew Feren
 Cetacean Networks, Inc.
 Portsmouth, NH