Re: [PATCH] send-email: restore --in-reply-to superseding behavior

> On Wed, Jun 24, 2020 at 02:33:14PM -0700, Junio C Hamano wrote:
> > Rafael Aquini <aquini@redhat.com> writes:
> > 
> > > git send-email --in-reply-to= fails to override the email headers,
> > > if they're present in the output of format-patch, which breakes the
> > 
> > Will do s/breakes/breaks/ while applying.
> >
> 
> UGH! I've been fat-fingering typos the whole day, today... Sorry about
> that one.
> 
>  
> > It makes me wonder, however, why it is a good idea to have the I-R-T
> > in the format patch output in the first place.
> > 
> > >  			elsif (/^In-Reply-To: (.*)/i) {
> > > -				$in_reply_to = $1;
> > > +				if (!$initial_in_reply_to) {
> > > +					$in_reply_to = $1;
> > > +				}
> > 
> > I can see how this would work the way it should for the first
> > message we send out, so it would work well for a single patch.
> > 
> > But what does this change do to the chaining (either making [PATCH
> > 1/N] thru [PATCH N/N] as responses to the cover letter [PATCH 0/N],
> > or making [PATCH n+1/N] as response to [PATCH n/N] for 1 <= n < N)
> > of multiple messages?
> > 
> > When you prepare a series whose 1..N/N are all pointing at 0/N with
> > the already prepared In-Reply-To (so you have N+1 files to send
> > out), wouldn't you want to make 0/N a reply to a particular message
> > you specify on the command line, while keeping the relationship
> > among your messages intact?  Doesn't having $initial_in_reply_to
> > (i.e. command line override) help above code break the chaning?
> >
> 
> This change will make all emails to appear as a reply to the msgid
> fed to --in-reply-to. I see your point, though, and at its light 
> I think now this patch, is actually incomplete. 
> 
> With this change we get back the override desired behavior,
> but it also breaks the contract, according to the man page.
> 
> "
>  --in-reply-to=<identifier>
>      Make the first mail (or all the mails with --no-thread) appear as a reply to the given Message-Id, which
>      avoids breaking threads to provide a new patch series. The second and subsequent emails will be sent as
>      replies according to the --[no-]chain-reply-to setting.
> "
> 
> I drove the change based on my usecase, which is marginal to the
> multi-part reply case. 
> 
> I guess we just need the following, for a complete solution:
> 
> 
> 
> diff --git a/git-send-email.perl b/git-send-email.perl
> index dc95656f75..768296ea0a 100755
> --- a/git-send-email.perl
> +++ b/git-send-email.perl
> @@ -1699,10 +1699,14 @@ sub process_file {
>  				$xfer_encoding = $1 if not defined $xfer_encoding;
>  			}
>  			elsif (/^In-Reply-To: (.*)/i) {
> -				$in_reply_to = $1;
> +				if (!$initial_in_reply_to || $thread) {
> +					$in_reply_to = $1;
> +				}
>  			}
>  			elsif (/^References: (.*)/i) {
> -				$references = $1;
> +				if (!$initial_in_reply_to || $thread) {
> +					$references = $1;
> +				}
>  			}
>  			elsif (!/^Date:\s/i && /^[-A-Za-z]+:\s+\S/) {
>  				push @xh, $_;