bug#13649: boobytrapped dired-do-async-shell-command question

[Lars Ingebrigtsen]

jidanni@jidanni.org writes:

> It sometimes will ask
> A command is running in the default buffer.  Use a new buffer? (yes or no)
>
> Which is a boobytrapped question, as picking "no" will always end up
> in failure...

I've now added help (on `C-h') on these prompts, which should hopefully
help people figure this out better.  Because I don't think there's any
way to explain it on one single prompt line.

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   bloggy blog: http://lars.ingebrigtsen.no