ns_memcached disconnect then rebalance fail

Control connection to memcached on 'ns_1@172.23.99.148' disconnected: {case_clause,

                                                                       [<<"active">>]}

...

[ns_server:error,2016-04-24T11:35:13.625-07:00,ns_1@172.23.99.148:<0.28937.29>:ns_single_vbucket_mover:spawn_and_wait:131]Got unexpected exit signal {'EXIT',<0.23592.21>,

                            {unexpected_exit,

                             {'EXIT',<0.4111.30>,

                              {{{badmatch,

                                 <<129,16,0,6,0,0,0,0,0,0,0,12,0,0,0,0,0,0,0,

..

                                   0,0,0,0,0,0,0,0,0,0>>},

                                {gen_server,call,

                                 ['ns_memcached-default',

                                  {get_dcp_docs_estimate,45,

                                   "replication:ns_1@172.23.99.148->ns_1@172.23.99.166:default"},

                                  180000]}},

                               {gen_server,call,

                                [{'janitor_agent-default',

                                  'ns_1@172.23.99.148'},

                                 {if_rebalance,<0.23592.21>,

                                  {wait_dcp_data_move,

                                   ['ns_1@172.23.99.166'],

                                   45}},

                                 infinity]}}}}}