bug#20237: Emacs built on Windows cannot figure out path correctly

[Eli Zaretskii <eliz@gnu.org>]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Tue, 31 Mar 2015 23:46:23 +0100
> 
> On Tue 31 Mar 2015, Eli Zaretskii wrote:
> 
> >> Date: Tue, 31 Mar 2015 13:52:20 -0400
> >> From: Da Zhang <zhangda82@gmail.com>
> >> 
> >> I am using Python mode in Emacs and wanted to start a python
> >> sub-process.
> >> However, Emacs could not find python.exe from the path I specified.
> >> Particularly, the following message was displayed:
> >> apply: Searching for program: no such file or directory,
> >> c\:/Python27/Scripts/ipython.exeInvalid face reference: python-cell
> >> 
> >> It seemed a "C\:" was added in front of the path to the python.
> >
> > You didn't say which path of Python did you specify, and how didyou
> > specify it.  Please tell, otherwise it's very hard to figure out the
> > reason for the problem.
> 
> I have seen something similar - I think it's caused by incorrect
> quoting:
> 
> --[python.el]-----------------------------------------------------------
> (defun python-shell-calculate-command ()
>   "Calculate the string used to execute the inferior Python process."
>   (let ((exec-path (python-shell-calculate-exec-path)))
>     ;; `exec-path' gets tweaked so that virtualenv's specific
>     ;; `python-shell-interpreter' absolute path can be found by
>     ;; `executable-find'.
>     (format "%s %s"
>             ;; FIXME: Why executable-find?
>             (shell-quote-argument
>              (executable-find python-shell-interpreter))
>             python-shell-interpreter-args)))
> --[python.el]-----------------------------------------------------------
> 
> Removing the use of shell-quote-argument seems to work around this
> problem.

I don't see why quoting here could do any harm.  Could you elaborate
on why you think it's wrong?