This patch (made against SOAPpy 0.12.0_rc1) makes
Client.py default to using the system-configured HTTP
proxy. The system-configured proxy is supplied by
urllib. This patch is complementary to patch #1083018,
which allows clients to consistently override the
system-configured proxy. Both patches should be applied.
The method that urllib uses to determine the
system-configured proxy is platform-dependent, but the
"http_proxy" environment variable is common.