Using cygwin bash shell with NT Emacs, path is not setup perfectly

[Eric Lilja <mindcooler@gmail.com>]

Hello, I'm using a native win32 version emacs and I want M-x shell to 
invoke Cygwin's bash instead of the default shell. Everything seems to 
work except that the path does not get setup properly.

Here's the output from echo $PATH when bash is run under nt emacs:
$ echo $PATH
/usr/bin:/usr/local/bin:/usr/bin:/usr/bin:/usr/X11R6/bin:/cygdrive/c/Program/MiKTeX 
2.6/miktex/bin:/cygdrive/c/WINDOWS/system32:/cygdrive/c/WINDOWS:/cygdrive/c/WINDOWS/System32/Wbem:/cygdrive/c/emacs/bin

Here's the same command when started using cygwin.bat:
$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/cygdrive/c/Program/MiKTeX 
2.6/miktex/bin:/cygdrive/c/WINDOWS/system32:/cygdrive/c/WINDOWS:/cygdrive/c/WINDOWS/System32/Wbem:/cygdrive/c/emacs/bin

See the difference? Under ntemacs I get /usr/bin twice in a row instead 
of /usr/bin:/bin:

This is causing problems for me. Why is this happening and how can I 
solve it?

Here's the relevant section of my .emacs. It's basically what's on the 
emacs wiki (I added ansi-color.for-comint-mode-on and removed the 
setting of the HOME variable as that is available anyway on my system):
(let* ((cygwin-root "c:/cygwin")
            (cygwin-bin (concat cygwin-root "/bin")))
       (setenv "PATH" (concat cygwin-bin ";" (getenv "PATH")))
       (setq exec-path (cons cygwin-bin exec-path))

      (setq shell-file-name "bash")
      (setq explicit-shell-file-name "bash")
      (add-hook 'comint-mode-hook 'ansi-color-for-comint-mode-on)))

Thanks for any replies.

- Eric