bug#19350: #19350 24.4; Incorrect quoting of %-signs for Windows command shell

[Noam Postavsky <npostavs@users.sourceforge.net>]

On Wed, Aug 17, 2016 at 10:02 PM, Demi Obenour <demiobenour@gmail.com> wrote:
> But *nix has no such feature [environment variables affect shell escaping], nor the associated gotcha.

I'm not sure what you're trying to point out here. Why does that
matter? We're talking about Windows, not *nix.

>
>
> On Aug 15, 2016 11:01 AM, "Eli Zaretskii" <eliz@gnu.org> wrote:
>>
>> > From: npostavs@users.sourceforge.net
>> > Date: Sun, 14 Aug 2016 23:13:43 -0400
>> > Cc: 19350@debbugs.gnu.org
>> >
>> > Hmm, maybe we could fix this by making Emacs refuse to apply environment
>> > variables with names ending in carets?
>>
>> I'm very much against disallowing perfectly valid (if rare) use cases
>> just because someone malicious can take advantage of that.
>>
>> From my POV, as long as Emacs itself doesn't produce such shell
>> commands and/or environment variables for any of its features,
>> avoiding this becomes user's responsibility, just like when working at
>> the shell prompt.  Of course, if we can find a reliable solution to
>> the problem that doesn't take away features, that'd be better, but
>> failing that, I'm okay with leaving this alone, perhaps documenting
>> somewhere that using % in shell commands when there are environment
>> variables ending in ^ could produce surprising results.
>>
>> Thanks.