Re: [PATCH] tag: fix sign_buffer() call to create a signed tag

> The command "git tag -s" internally calls sign_buffer() to make a
> cryptographic signature using the chosen backend like GPG and SSH.
> The internal helper functions used by "git tag" implementation seem
> to use a "negative return values are errors, zero or positive return
> values are not" convention, and there are places (e.g., verify_tag()
> that calls gpg_verify_tag()) that these internal helper functions
> translate return values that signal errors to conform to this
> convention, but do_sign() that calls sign_buffer() forgets to do so.
> 
> Fix it, so that a failed call to sign_buffer() that can return the
> exit status from pipe_command() will not be overlooked.
> 
> Reported-by: Sergey Kosukhin <skosukhin@gmail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
> 
>  * We alternatively could fix individual sign_buffer() backend that
>    signals an error with a positive value (sign_buffer_ssh() in this
>    case) to return a negative value, but this would hopefully be
>    more future-proof.