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.

#!/usr/bin/env python
from __future__ import print_function
import zlib, base64, sys
print(base64.encodestring(zlib.compress(sys.stdin.read())))