Fix Python tests on MS-Windows

Fix Python tests on MS-Windows

* test/automated/python-tests.el
(python-shell-calculate-command-1): Run python-shell-interpreter
through shell-quote-argument before comparing with what
python-shell-calculate-command returns.
(python-shell-calculate-pythonpath-1)
(python-shell-calculate-pythonpath-2)
(python-shell-calculate-process-environment-2): Use path-separator
instead of a literal ':'.
(python-shell-calculate-exec-path-2)
(python-shell-calculate-exec-path-3)
(python-shell-calculate-exec-path-4)
(python-shell-with-environment-1)
(python-shell-with-environment-2): Run "/env/bin" through
expand-file-name before comparing with exec-path.  (Bug#21375)