Fixed issue with worker-thread test not terminating the thread.
Fixed issue with worker-thread test not terminating the thread.

Change-Id: I03c1f4616c0d2c628a808b0b5acaeaf5849f80fa
Reviewed-on: https://review.couchbase.org/c/couchnode/+/167812
Reviewed-by: Jared Casey <07fbe21933bc3411328c4385bc2be7d6649bbd1d@couchbase.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

couchbase/couchnode,brett19/couchnode,couchbase/couchnode,brett19/couchnode,couchbase/couchnode,couchbase/couchnode,brett19/couchnode