Function update_head

builtin/clone.c:572–613

}

static void update_head(struct clone_opts *opts, const struct ref *our, const struct ref *remote,
			const char *unborn, const char *msg)
{
	const char *head;
	if (our && !opts->detach && skip_prefix(our->name, "refs/heads/", &head)) {
		/* Local default branch link */
		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", our->name, NULL) < 0)
			die(_("unable to update HEAD"));
		if (!option_bare) {
			refs_update_ref(get_main_ref_store(the_repository),
					msg, "HEAD", &our->old_oid, NULL, 0,
					UPDATE_REFS_DIE_ON_ERR);
			install_branch_config(0, head, remote_name, our->name);
		}
	} else if (our) {
		struct commit *c = lookup_commit_or_die(&our->old_oid,
							our->name);

		/* --branch specifies a non-branch (i.e. tags), detach HEAD */
		refs_update_ref(get_main_ref_store(the_repository), msg,
				"HEAD", &c->object.oid, NULL, REF_NO_DEREF,
				UPDATE_REFS_DIE_ON_ERR);
	} else if (remote) {
		/*
		 * We know remote HEAD points to a non-branch, or
		 * HEAD points to a branch but we don't know which one.
		 * Detach HEAD in all these cases.
		 */
		refs_update_ref(get_main_ref_store(the_repository), msg,
				"HEAD", &remote->old_oid, NULL, REF_NO_DEREF,
				UPDATE_REFS_DIE_ON_ERR);
	} else if (unborn && skip_prefix(unborn, "refs/heads/", &head)) {
		/*
		 * Unborn head from remote; same as "our" case above except
		 * that we have no ref to update.
		 */
		if (refs_update_symref(get_main_ref_store(the_repository), "HEAD", unborn, NULL) < 0)
			die(_("unable to update HEAD"));
		if (!option_bare)
			install_branch_config(0, head, remote_name, unborn);
	}
}

static int git_sparse_checkout_init(const char *repo)
{