push --force-with-lease: tie it all together

This teaches the deepest part of the callchain for "git push" (and
"git send-pack") to enforce "the old value of the ref must be this,
otherwise fail this push" (aka "compare-and-swap" / "--lockref").

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/transport.c b/transport.c
index 5dd92b7..b321d6a 100644
--- a/transport.c
+++ b/transport.c
@@ -709,6 +709,10 @@
 		print_ref_status('!', "[rejected]", ref, ref->peer_ref,
 						 "needs force", porcelain);
 		break;
+	case REF_STATUS_REJECT_STALE:
+		print_ref_status('!', "[rejected]", ref, ref->peer_ref,
+						 "stale info", porcelain);
+		break;
 	case REF_STATUS_REMOTE_REJECT:
 		print_ref_status('!', "[remote rejected]", ref,
 						 ref->deletion ? NULL : ref->peer_ref,
@@ -1078,6 +1082,7 @@
 	for (r = remote_refs; r; r = r->next) {
 		if (!r->peer_ref) continue;
 		if (r->status == REF_STATUS_REJECT_NONFASTFORWARD) continue;
+		if (r->status == REF_STATUS_REJECT_STALE) continue;
 		if (r->status == REF_STATUS_UPTODATE) continue;
 
 		strbuf_reset(&buf);