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

[Eli Zaretskii <eliz@gnu.org>]

> Date: Wed, 01 Apr 2015 09:50:23 -0400
> From: Da Zhang <zhangda82@gmail.com>
> CC: 20237@debbugs.gnu.org
> 
> The commands I used were: 
> elpy-shell-send-region-or-buffer
> and
> elpy-shell-switch-to-shell
> 
> Under previous Emacs version 24.4.90, the same package and command worked fine. 

What does the following command display?

  M-: (python-shell-parse-command) RET

Also, what does this display?

  M-: (split-string-and-unquote (python-shell-parse-command)) RET

Please also note that you configured python.el to use the ipython
script as the interpreter, which AFAIK is not a .exe program, whereas
the error message you cited:

  apply: Searching for program: no such file or directory,
  c\:/Python27/Scripts/ipython.exe

seems to indicate that Emacs tries to look for a .exe program there,
or perhaps it doesn't recognize ipython the script as a program.  Not
sure if this is relevant to the problem.

Finally, can you set debug-on-error to t, load both python.el and
elpy.el as .el files (NOT .elc!), and then reproduce the problem and
show the full backtrace that the debugger displays?

Thanks.