PYCBC-197: Don't modify remaining count on lcb_wait failure

Change-Id: Iec44b9e9fa40e12baef5f18e0eb1ef0a8379a05d
Reviewed-on: http://review.couchbase.org/29459
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>