urllib.py uses "*_proxy" variables to identify proxies
to use in the "getproxies()" function. However, it does
not use the corresponding "no_proxy" variable in the
"proxy_bypass()" method.

This affects any platform that can use "*_proxy"
environment variables to specify proxies. This includes
win32, which will use environment variables before the
registry if they are defined.

On win32 this causes the confusing behaviour of using
the registry for "proxy_bypass()" checking when
"*_proxy" environment variables are used to identify
the proxies.

Attached is a patch against python-2.3.2 that adds
support for "no_proxy". Note that win32 will correctly
favor using "no_proxy" over using the registry if any
"*_proxy" variables are defined.