Review of add-randomization-(...).patch:
 - there is a missing ")" in the doc, near "the types covered by the :option:`-R` option (or its equivalent, :envvar:`PYTHONHASHRANDOMIZATION`."
 - get_hash() in test_hash.py fails completly on Windows: Windows requires some environment variables. Just use env=os.environ.copy() instead of env={}.
 - PYTHONHASHSEED doc is not clear: it should be mentionned that the variable is ignored if PYTHONHASHRANDOMIZATION is not set
 - (Python 2.6) test_hash fails because of "[xxx refs]" in stderr if Python is compiled in debug mode. Add strip_python_stderr() to test_support.py and use it in get_hash().

def strip_python_stderr(stderr):
    """Strip the stderr of a Python process from potential debug output
    emitted by the interpreter.

    This will typically be run on the result of the communicate() method
    of a subprocess.Popen object.
    """
    stderr = re.sub(br"\[\d+ refs\]\r?\n?$", b"", stderr).strip()
    return stderr

Except these minor nits, the patches (2.6 and 3.1) looks good. I didn't read the tests patches: just run the tests to test them :-) (Or our buildbots will do the work for you.)