Fix 'git remote show' regression on empty repository in 1.5.4

Back in 18f7c51 we switched git-ls-remote/git-peek-remote to
use the transport backend, rather than do everything itself.

As part of that switch we started to produce a non-zero exit
status if no refs were received from the remote peer, which
happens when the remote peer has no commits pushed to it yet.
(E.g. "git --git-dir=foo.git init; git ls-remote foo.git")

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-ls-remote.c

@@ -94,10 +94,6 @@ int cmd_ls_remote(int argc, const char **argv, const char *prefix)
 		transport_set_option(transport, TRANS_OPT_UPLOADPACK, uploadpack);
 
 	ref = transport_get_remote_refs(transport);
-
-	if (!ref)
-		return 1;
-
 	for ( ; ref; ref = ref->next) {
 		if (!check_ref_type(ref, flags))
 			continue;