bug#25025: python-shell-calculate-command is wrong

[npostavs]

Eli Zaretskii <eliz@gnu.org> writes:
>
> So the problematic scenario is that the user sets
> python-shell-interpreter to something we already checked, and then
> manually feeds us with a command that invokes a different Python
> interpreter, is that it?  Is that a frequent use case, which we
> should care about?  Just to produce a warning?
>
> Even if we do want to care about, we could try matching the beginning
> of the command, perhaps after an optional quote character, and if we
> don't recognize the interpreter, do nothing.  Would that be
> sufficient?

To be honest, I don't use python enough to say what the best fix is
here.  I can say that the easiest way to solve this bug is:

--- a/lisp/progmodes/python.el
+++ b/lisp/progmodes/python.el
@@ -2379,7 +2379,7 @@ python-shell-internal-get-process-name
 (defun python-shell-calculate-command ()
   "Calculate the string used to execute the inferior Python process."
   (format "%s %s"
-          (shell-quote-argument python-shell-interpreter)
+          (combine-and-quote-strings (list python-shell-interpreter))
           python-shell-interpreter-args))