MB-42725 Fix panic on Unlock of unlock of RWMutex
MB-42725 Fix panic on Unlock of unlock of RWMutex

Change-Id: I6794a15aba245483376f85b4a65fff0f11e5a049
Reviewed-on: http://review.couchbase.org/c/go-couchbase/+/140160
Reviewed-by: Sitaram Vemulapalli <8d86a491dcdf321bac78bef141a8229a59bf9211@couchbase.com>
Tested-by: Isha Kandaswamy <e3cc845ebc6144fc4d71cf5f07a0ce9db6fdfa91@couchbase.com>

couchbase/go-couchbase