badarith in ns_doctor's task aggregation code

Seen this myself once on my own box and now second time in Tony's cluster:

Server error during processing: ["web request failed",

{path,"/pools/default/tasks"}

,

{type,error}

,

{what,badarith}

,
{trace,
[

{ns_doctor,finalize_indexer_or_compaction, 4}

,

{ns_doctor, '-do_build_tasks_list/3-fun-4-',4}

,

{dict,fold_bucket,3}

,

{dict,fold_seg,4}

,

{dict,fold_segs,4}

,

{ns_doctor,do_build_tasks_list,3}

,

{menelaus_web,handle_tasks,2}

,

{menelaus_web,loop,3}

]}] menelaus_web019 ns_1@10.3.121.13 19:46:44 - Mon Aug 13, 2012
Bucket "default" loaded on node 'ns_1@10.3.121.25' in 754 seconds. ns_memcached001 ns_1@10.3.121.25 19:44:05 - Mon Aug 13, 2012