Windows requires at least the SYSTEMROOT environment variable to start Python.
If run_python_until_end() doesn't copy SYSTEMROOT, the function always fail on
Windows.
If Popen.communicate() raises an exception, kill the child process to not leave
a running child process in background and maybe create a zombi process.
This change fixes a ResourceWarning in Python 3.6 when unit tests are
interrupted by CTRL+c.
parameter to "enable" the always on sys.flags.hash_randomization
in _args_from_interpreter_flags() used by multiprocessing and
some unittests. This simplifies the code.
* assert_python_ok docstring typo fix.
* Fix test_cmd_line not to fail if PYTHONHASHSEED is set to a fixed seed.