Don't flood the console with EBUSY/ETMPFAIL

These messages pop up a lot when you start hitting the cluster
hard anyway.

Change-Id: If5b9d1507d1488be80b6a56f77ecf4f393b3d1ab
Reviewed-on: http://review.couchbase.org/40745
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>