issue2551212 - enable wsgi cache_tracker by default Switch the code so the wsgi cache_tracker optimization is enabled by default. Leave the unoptimized/uncached code path available in case it breaks something. The feature flag can be set to False to disable caching. Updated tests to test the disabled (non-cache) code path. Updated upgrading.txt with info on how to disable caching.

try:
    # Python 3+.
    from xmlrpc import client, server
    server.SimpleXMLRPCDispatcher
except (ImportError, AttributeError):
    # Python 2.
    import xmlrpclib as client  # noqa: F401
    import SimpleXMLRPCServer as server