Deadlock between ReplicaSetMonitor updating the connection string for a shard and reloading the ShardRegistry

 [2016/02/24 15:16:18.727] Thread 10 (Thread 0x2b4968191940 (LWP 15297)):

 [2016/02/24 15:16:18.727] #0  0x00002b495f481654 in __lll_lock_wait () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.727] #1  0x00002b495f47cf4a in _L_lock_1034 () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.727] #2  0x00002b495f47ce0c in pthread_mutex_lock () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.727] #3  0x0000000000701dd8 in mongo::ReplicaSetMonitor::getServerAddress() const

 [2016/02/24 15:16:18.727]     ()

 [2016/02/24 15:16:18.727] #4  0x00000000006ffc66 in mongo::RemoteCommandTargeterRS::connectionString()

 [2016/02/24 15:16:18.727]     ()

 [2016/02/24 15:16:18.727] #5  0x0000000000af3e57 in mongo::ShardRegistry::_updateLookupMapsForShard_inlock(std::shared_ptr<mongo::Shard>, boost::optional<mongo::ConnectionString const&>) ()

 [2016/02/24 15:16:18.727] #6  0x0000000000af4770 in mongo::ShardRegistry::_addShard_inlock(mongo::ShardType const&, bool) ()

 [2016/02/24 15:16:18.727] #7  0x0000000000af55ad in mongo::ShardRegistry::reload(mongo::OperationContext*) ()

 [2016/02/24 15:16:18.728] #8  0x0000000000a27dd6 in mongo::Balancer::run() ()

 [2016/02/24 15:16:18.728] #9  0x0000000000bc4d80 in mongo::BackgroundJob::jobBody() ()

 [2016/02/24 15:16:18.728] #10 0x0000000000e15190 in execute_native_thread_routine ()

 [2016/02/24 15:16:18.728] #11 0x00002b495f47a83d in start_thread () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.728] #12 0x00002b495f764fdd in clone () from /lib64/libc.so.6

 [2016/02/24 15:16:18.728] #13 0x0000000000000000 in ?? ()

 [2016/02/24 15:16:18.731] Thread 5 (Thread 0x2b496a995940 (LWP 15448)):

 [2016/02/24 15:16:18.731] #0  0x00002b495f481654 in __lll_lock_wait () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.731] #1  0x00002b495f47cf4a in _L_lock_1034 () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.732] #2  0x00002b495f47ce0c in pthread_mutex_lock () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.732] #3  0x0000000000af3152 in mongo::ShardRegistry::lookupRSName(std::string const&) const ()

 [2016/02/24 15:16:18.732] #4  0x0000000000b5061f in mongo::ConfigServer::replicaSetChangeShardRegistryUpdateHook(std::string const&, std::string const&) ()

 [2016/02/24 15:16:18.732] #5  0x0000000000707884 in mongo::ReplicaSetMonitor::Refresher::receivedIsMasterFromMaster(mongo::ReplicaSetMonitor::IsMasterReply const&) ()

 [2016/02/24 15:16:18.732] #6  0x0000000000708313 in mongo::ReplicaSetMonitor::Refresher::receivedIsMaster(mongo::HostAndPort const&, long, mongo::BSONObj const&) ()

 [2016/02/24 15:16:18.732] #7  0x000000000070890d in mongo::ReplicaSetMonitor::Refresher::_refreshUntilMatches(mongo::ReadPreferenceSetting const*) ()

 [2016/02/24 15:16:18.732] #8  0x00000000007096c1 in mongo::(anonymous namespace)::ReplicaSetMonitorWatcher::run() ()

 [2016/02/24 15:16:18.732] #9  0x0000000000bc4d80 in mongo::BackgroundJob::jobBody() ()

 [2016/02/24 15:16:18.732] #10 0x0000000000e15190 in execute_native_thread_routine ()

 [2016/02/24 15:16:18.732] #11 0x00002b495f47a83d in start_thread () from /lib64/libpthread.so.0

 [2016/02/24 15:16:18.732] #12 0x00002b495f764fdd in clone () from /lib64/libc.so.6

 [2016/02/24 15:16:18.732] #13 0x0000000000000000 in ?? ()