MB-10730 Fix a upr status code in upr fake_server

Change-Id: Iaa69f11917026b165d341268ecefdbd917f18a19
Reviewed-on: http://review.couchbase.org/35548
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>