upload-pack: drop lookup-before-parse optimization

When we receive a "have" line from the client, we want to load the object pointed to by the sha1. However, we are careful to do: o = lookup_object(sha1); if (!o || !o->parsed) o = parse_object(sha1); to avoid loading the object from disk if we have already seen it. However, since ccdc603 (parse_object: try internal cache before reading object db), parse_object already does this optimization internally. We can just call parse_object directly. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>