$ ./mongos --configdb "configRepl/localhost:20000"
2015-06-11T17:00:54.620-0700 W SHARDING [main] running with less than 3 config servers should be done only for testing purposes and is not recommended for production
2015-06-11T17:00:54.625-0700 I CONTROL  [main] 
2015-06-11T17:00:54.625-0700 I CONTROL  [main] ** NOTE: This is a development version (3.1.5-pre-) of MongoDB.
2015-06-11T17:00:54.625-0700 I CONTROL  [main] **       Not recommended for production.
2015-06-11T17:00:54.625-0700 I CONTROL  [main] 
2015-06-11T17:00:54.625-0700 I SHARDING [mongosMain] MongoS version 3.1.5-pre- starting: pid=24844 port=27017 64-bit host=behackett-dt (--help for usage)
2015-06-11T17:00:54.625-0700 I CONTROL  [mongosMain] db version v3.1.5-pre-
2015-06-11T17:00:54.625-0700 I CONTROL  [mongosMain] git version: 2cd33990466931e4ac06ddeedbdf217885eec1cb
2015-06-11T17:00:54.625-0700 I CONTROL  [mongosMain] OpenSSL version: OpenSSL 1.0.1m 19 Mar 2015
2015-06-11T17:00:54.625-0700 I CONTROL  [mongosMain] allocator: tcmalloc
2015-06-11T17:00:54.625-0700 I CONTROL  [mongosMain] options: { sharding: { configDB: "configRepl/localhost:20000" } }
2015-06-11T17:00:54.626-0700 I NETWORK  [mongosMain] starting new replica set monitor for replica set configRepl with seeds 
2015-06-11T17:00:54.626-0700 I NETWORK  [mongosMain] localhost:20000
2015-06-11T17:00:54.626-0700 I NETWORK  [ReplicaSetMonitorWatcher] starting
2015-06-11T17:00:54.626-0700 I NETWORK  [mongosMain] changing hosts to configRepl/behackett-dt:20000 from configRepl/localhost:20000
2015-06-11T17:00:54.626-0700 F -        [replSetChange] Invalid access at address: 0x30
2015-06-11T17:00:54.628-0700 F -        [replSetChange] Got signal: 11 (Segmentation fault).

 0xa6d886 0xa6cfa2 0xa6d2de 0x7f811aac5d30 0x7f811aac0047 0x949d68 0x943a47 0x99e5e4 0xabd5d3 0x7f811aabe204 0x7f811a80539d
----- BEGIN BACKTRACE -----
{"backtrace":[{"b":"400000","o":"66D886"},{"b":"400000","o":"66CFA2"},{"b":"400000","o":"66D2DE"},{"b":"7F811AAB6000","o":"FD30"},{"b":"7F811AAB6000","o":"A047"},{"b":"400000","o":"549D68"},{"b":"400000","o":"543A47"},{"b":"400000","o":"59E5E4"},{"b":"400000","o":"6BD5D3"},{"b":"7F811AAB6000","o":"8204"},{"b":"7F811A71E000","o":"E739D"}],"processInfo":{ "mongodbVersion" : "3.1.5-pre-", "gitVersion" : "2cd33990466931e4ac06ddeedbdf217885eec1cb", "compiledModules" : [ "subscription" ], "uname" : { "sysname" : "Linux", "release" : "3.18.12-gentoo", "version" : "#2 SMP PREEMPT Tue May 26 15:22:47 PDT 2015", "machine" : "x86_64" }, "somap" : [ { "elfType" : 2, "b" : "400000" }, { "b" : "7FFC3E326000", "path" : "linux-vdso.so.1", "elfType" : 3, "buildId" : "0A7A2A573DB41C758905DBB4FB669EBBCC015F22" }, { "b" : "7F811C17F000", "path" : "/usr/lib64/libsasl2.so.3", "elfType" : 3 }, { "b" : "7F811BF36000", "path" : "/usr/lib64/libgssapi_krb5.so.2", "elfType" : 3 }, { "b" : "7F811BCC7000", "path" : "/usr/lib64/libssl.so.1.0.0", "elfType" : 3 }, { "b" : "7F811B8F7000", "path" : "/usr/lib64/libcrypto.so.1.0.0", "elfType" : 3 }, { "b" : "7F811B6EF000", "path" : "/lib64/librt.so.1", "elfType" : 3 }, { "b" : "7F811B4EB000", "path" : "/lib64/libdl.so.2", "elfType" : 3 }, { "b" : "7F811B1E7000", "path" : "/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/libstdc++.so.6", "elfType" : 3 }, { "b" : "7F811AEE7000", "path" : "/lib64/libm.so.6", "elfType" : 3 }, { "b" : "7F811ACD1000", "path" : "/usr/lib/gcc/x86_64-pc-linux-gnu/4.8.4/libgcc_s.so.1", "elfType" : 3 }, { "b" : "7F811AAB6000", "path" : "/lib64/libpthread.so.0", "elfType" : 3 }, { "b" : "7F811A71E000", "path" : "/lib64/libc.so.6", "elfType" : 3 }, { "b" : "7F811C39C000", "path" : "/lib64/ld-linux-x86-64.so.2", "elfType" : 3 }, { "b" : "7F811A507000", "path" : "/lib64/libresolv.so.2", "elfType" : 3 }, { "b" : "7F811A234000", "path" : "/usr/lib64/libkrb5.so.3", "elfType" : 3 }, { "b" : "7F811A003000", "path" : "/usr/lib64/libk5crypto.so.3", "elfType" : 3 }, { "b" : "7F8119DFF000", "path" : "/lib64/libcom_err.so.2", "elfType" : 3 }, { "b" : "7F8119BF3000", "path" : "/usr/lib64/libkrb5support.so.0", "elfType" : 3 }, { "b" : "7F81199EF000", "path" : "/lib64/libkeyutils.so.1", "elfType" : 3 }, { "b" : "7F81197D9000", "path" : "/lib64/libz.so.1", "elfType" : 3 }, { "b" : "7F81195D4000", "path" : "/usr/lib64/sasl2/liblogin.so", "elfType" : 3 }, { "b" : "7F8119377000", "path" : "/lib64/libcrypt.so.1", "elfType" : 3 }, { "b" : "7F8119170000", "path" : "/usr/lib64/sasl2/libsasldb.so", "elfType" : 3 }, { "b" : "7F8118F64000", "path" : "/usr/lib64/libgdbm.so.4", "elfType" : 3 }, { "b" : "7F8118D5F000", "path" : "/usr/lib64/sasl2/libanonymous.so", "elfType" : 3 }, { "b" : "7F8118B59000", "path" : "/usr/lib64/sasl2/libcrammd5.so", "elfType" : 3 }, { "b" : "7F8118950000", "path" : "/usr/lib64/sasl2/libntlm.so", "elfType" : 3 }, { "b" : "7F811874A000", "path" : "/usr/lib64/sasl2/libsql.so", "elfType" : 3 }, { "b" : "7F8118481000", "path" : "/usr/lib64/libsqlite3.so.0", "elfType" : 3 }, { "b" : "7F8118026000", "path" : "/usr/lib64/libicui18n.so.55", "elfType" : 3 }, { "b" : "7F8117C99000", "path" : "/usr/lib64/libicuuc.so.55", "elfType" : 3 }, { "b" : "7F81161E2000", "path" : "/usr/lib64/libicudata.so.55", "elfType" : 3 }, { "b" : "7F8115FD8000", "path" : "/usr/lib64/sasl2/libscram.so", "elfType" : 3 }, { "b" : "7F8115DCA000", "path" : "/usr/lib64/sasl2/libdigestmd5.so", "elfType" : 3 }, { "b" : "7F8115BC1000", "path" : "/usr/lib64/sasl2/libgs2.so", "elfType" : 3 }, { "b" : "7F81159BC000", "path" : "/usr/lib64/sasl2/libplain.so", "elfType" : 3 }, { "b" : "7F81157A2000", "path" : "/usr/lib64/sasl2/libotp.so", "elfType" : 3 }, { "b" : "7F8115599000", "path" : "/usr/lib64/sasl2/libgssapiv2.so", "elfType" : 3 } ] }}
 mongos(_ZN5mongo15printStackTraceERSo+0x26) [0xa6d886]
 mongos(+0x66CFA2) [0xa6cfa2]
 mongos(+0x66D2DE) [0xa6d2de]
 libpthread.so.0(+0xFD30) [0x7f811aac5d30]
 libpthread.so.0(pthread_mutex_lock+0x7) [0x7f811aac0047]
 mongos(_ZN5mongo13ShardRegistry12lookupRSNameERKSs+0x28) [0x949d68]
 mongos(_ZN5mongo5Shard12lookupRSNameERKSs+0x17) [0x943a47]
 mongos(_ZN5mongo12ConfigServer16replicaSetChangeERKSsS2_+0x44) [0x99e5e4]
 mongos(+0x6BD5D3) [0xabd5d3]
 libpthread.so.0(+0x8204) [0x7f811aabe204]
 libc.so.6(clone+0x6D) [0x7f811a80539d]
-----  END BACKTRACE  -----