rebalance fails with mover_failed

1) install membase on node1
2) create a bucket
3) add a few keys to the bucket
4) install membase on node2
5) add node2 and rebalance

Rebalance exited with reason {mover_failed,
{function_clause,
[{ebucketmigrator_srv,process_upstream,
[<<129,64,0,0,0,0,0,131,0,0,0,13,0,0,0,0,0,0,
0,0,0,0,0,0,78,111,116,32,115,117,112,112,
111,114,116,101,100>>,
{state,0,#Port<0.7764>,#Port<0.7763>,<<>>,
<<>>,
{set,1,16,16,8,80,48,

{[],[],[],[],[],[],[],[],[],[],[],[],[], [],[],[]}

,
{{[],[],[],[],[],[],
[512],
[],[],[],[],[],[],[],[],[]}}},
-1,true,false,0,

{1305,756943,311343}

,
undefined}]},

{ebucketmigrator_srv,process_data,3}

,

{ebucketmigrator_srv,process_data,4}

,

{ebucketmigrator_srv,handle_info,2}

,

{gen_server,handle_msg,5}

,

{proc_lib,init_p_do_apply,3}

]}}

Possibly related to MB-3866

The systems seem unable to generate diags at this point.