Re: [PATCH v3] send-email: add --confirm option and configuration setting

> Unfortunately, it is impossible to introduce this patch such that it
> helps new users without potentially annoying some existing users. We
> attempt to mitigate the latter by:
>
>  * Allowing the user to set 'git config sendemail.confirm never'
>  * Allowing the user to say 'all' after the first prompt to not be
>    prompted on remaining emails during the same invocation.
>  * Telling the user about the 'sendemail.confirm' setting if it is
>    unconfigured whenever we prompt due to Cc before sending.
>  * Only prompting if no --suppress related options have been passed, as
>    using such an option is likely to indicate an experienced send-email
>    user.
>
> There is a slight fib in message informing the user of the
> sendemail.confirm setting and this is intentional. Setting 'auto'
> differs from leaving sendemail.confirm unset in two ways: 1) 'auto'
> obviously squelches the informational message; 2) 'auto' prompts when
> the Cc list has been expanded even in the presence of a --suppress
> related option, where leaving sendemail.confirm unset does not. This is
> intentional to keep the message simple, and to avoid adding another
> sendemail.confirm value ('auto-except-suppress'?).