Re: [PATCH 5/6 (v2)] upload-pack: send the HEAD information

"Shawn O. Pearce" [off-list ref] writes:

Maybe we put on the first capability line a flag that lets the
client know we have symref data in the advertised list, and then
instead of sticking only HEAD into that first ref we put the names
of the symrefs after the ref they point to.

So we might see something like:

  xxxx......................... refs/heads/boo\0with-symref\0
  xxxx......................... refs/heads/master\0HEAD\0
  xxxx......................... refs/remotes/origin/HEAD\0refs/remotes/origin/master\0

etc.  Its probably harder to produce the output for, but it permits
advertising all of the symrefs on the remote side, which may be good
for --mirror, among other uses.  It also should make it easier to put
multiple symrefs down pointing at the same real ref, they could just
be a space delimited list stored after the ref name, and if its the
first ref in the stream, after the other capability advertisement.

It certainly is possible, and I think the arrangement v2 code makes
already keeps that option to talk about symrefs other than HEAD open.  If
you want to send all the symref information, you would show something
like:

    xxxx... HEAD\0<caps>\0refs/heads/master\n
    xxxx... refs/heads/master\n
    xxxx... refs/remotes/origin/HEAD\0<caps>\0refs/remotes/origin/master\n
    xxxx... refs/remotes/origin/master\n

But in this round I am not interested in giving any "random symref"
information but "HEAD", so I omitted it from the code.  

Notice that you need to repeat the capabilities list on each and every
line that describes a symbolic ref for that to work (and you do not need
"with-symref"), though.  See what ll. 80-84 in connect.c does.

	if (len != name_len + 41) {
		free(server_capabilities);
		server_capabilities = xstrdup(name + name_len + 1);
	}

Historical accident mandates that the first hidden piece of information on
each and all of these lines _must_ be the capabilities list.