Re: [PATCH v2 1/3] ls-refs: report unborn targets of symrefs

On Tue, Dec 15, 2020 at 06:07:56PM -0800, Jonathan Tan wrote:

quoted

+static int ls_refs_config(const char *var, const char *value, void *cb_data)
+{
+	struct ls_refs_data *data = cb_data;
+
+	if (!strcmp("lsrefs.unborn", var))
+		data->allow_unborn = !strcmp(value, "allow") ||
+			!strcmp(value, "advertise");

What's the reason we would want this to be configurable? I would think
we would just want it always on for the server, and then clients can
choose to make us of it or not (and probably not by omitting the
capability; the question is what they want to do with the information
about HEAD, but that is true whether it is unborn or not, and is
controlled by options like "clone -b").

Firstly, this allows a staged rollout in load-balancing situations
wherein we turn on "allow" for all servers, then "advertise", so that we
don't end up with a client that sees the advertisement but then sends
the follow-up request to a server that has not received the latest
configuration yet.

Secondly, I wonder if some people purposely set HEAD to an unborn branch
just so that the repository would be presented as not having a HEAD.
Now, the name of the unborn branch would be revealed. I don't know if
that's a problem, though - but if it is, at least this configuration
variable is a way to solve that.

I'll include this in the documentation in a next version of this patch
set.