bug#20744: shell-quote-argument in Emacs 24.5 and Emacs 25 on Windows cannot figure out path correctly

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Cc: Da Zhang <zhangda82@gmail.com>,  20744@debbugs.gnu.org
> Date: Sun, 07 Jun 2015 14:01:31 -0400
> 
> Eli Zaretskii wrote:
> 
> > I'm sorry, but I don't see how we can accept such a change: it means
> > that when the Cygwin Bash is used as the shell, the ':' character will
> > not be quoted, which I think could cause trouble in some cases.
> >
> > Maybe some Bash expert could chime in and tell whether problems are
> > possible with Bash in this case.
> 
> Not an expert (and didn't read the rest of the report), but I can't
> think of a reason why ':' would need quoting in Bash (unlike eg ';' or '&').
> What kind of thing are you thinking of?

PATH-style lists, maybe.

Anyway, if we think ':' doesn't need to be quoted, how about removing
it from the Posix branch of shell-quote-argument?  Then we won't need
ugly hacks that try to detect Cygwin Bash used from a native Windows
Emacs.