Re: cannot clone --single-commit instead of --single-branch

[Jonathan Nieder]

(cc: Duy, who might enjoy this walk through history)
Hi,

Alexander Mills wrote:

> git clone --single-branch=<sha>
>
> doesn't seem to work?

I've occasionally wanted something like this (actually, I've wanted to
pass a refname like "refs/meta/config").  builtin/clone.c contains

        static struct ref *find_remote_branch(const struct ref *refs, const 
char *branch)
        {
                struct ref *ref;
                struct strbuf head = STRBUF_INIT;
                strbuf_addstr(&head, "refs/heads/");
                strbuf_addstr(&head, branch);
                ref = find_ref_by_name(refs, head.buf);
                strbuf_release(&head);

                if (ref)
                        return ref;

So far, what one would expect.

                strbuf_addstr(&head, "refs/tags/");
                strbuf_addstr(&head, branch);
                ref = find_ref_by_name(refs, head.buf);
                strbuf_release(&head);

Wait a second: a tag isn't a branch, so why do we accept it as a
value for --branch?  So this is stretching definitions a little
already.

"git log -L:find_remote_branch:builtin/clone.c" tells me this is from
v1.7.10-rc0~125^2~3 (clone: allow --branch to take a tag, 2012-01-16):

        Because a tag ref cannot be put to HEAD, HEAD will become detached.
        This is consistent with "git checkout <tag>".

I think ideally we could first check for a sha1 and then try the full
set of patterns from ref_rev_parse_rules.  What do you think?  Would
you be interested in taking a stab at it?

Thanks,
Jonathan