memcached silently closes connection in auth request [was: ns_server: throws exception in ebucketmigrator_srv during rebalance test]

Rebalance-in while inserting spatial docs causes rebalance to fail. During the time of failure, I see the following in the diags:

[error_logger:error] [2012-02-21 10:49:04] [n_0@10.17.4.51:error_logger:ale_error_logger_handler:log_report:72]
=========================CRASH REPORT=========================
crasher:
initial call: ebucketmigrator_srv:init/1
pid: <0.25874.6>
registered_name: []
exception error: no match of right hand side value

in function mc_client_binary:cmd_binary_vocal_recv/5 (src/mc_client_binary.erl, line 103)
in call from mc_client_binary:auth/2 (src/mc_client_binary.erl, line 145)
in call from ebucketmigrator_srv:connect/4 (src/ebucketmigrator_srv.erl, line 281)
in call from ebucketmigrator_srv:init/1 (src/ebucketmigrator_srv.erl, line 133)
ancestors: [<0.25873.6>]
messages: []
links: Port<0.454477>,<0.25873.6>,#Port<0.454476>
dictionary: []
trap_exit: false
status: running
heap_size: 987
stack_size: 24
reductions: 960
neighbours:

SpatialRebalanceTests.test_insert_x_docs_during_rebalance