Falls back to vendor passthru on receiving 404.
Also fixes logging around lookup: log traceback on unexpected
exceptions, log successful lookup and replace % with ,
Change-Id: I7160c99ca63585fc333482fa578fdf5e0962b2b6
Depends-On: I9080c07b03103cd7a323e2fc01be821733b07eea
Partial-Bug: #1570841