fix _get_buckets in active_tasks
fix _get_buckets in active_tasks

Change-Id: I0d696798eebf77b6c5b353b9e685b076faa5a966
Reviewed-on: http://review.couchbase.org/24803
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Pavel Paulau <dd88eded64e90046a680e3a6c0828ceb8fe8a0e7@gmail.com>

ronniedada/litmus,ronniedada/litmus,couchbase/cbmonitor,couchbase/cbagent,couchbase/cbmonitor,vmx/cbagent,mikewied/cbagent,pavel-paulau/cbagent