Using the --discover flag on mongostat in a kerberos environment results in multiple exceptions:
[ec2-user@mongod1 ~]$ ./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat --authenticationMechanism=GSSAPI --authenticationDatabase='$external' --username grund/admin@REALM99.10GEN.ME --host mongod1.realm99.10gen.me --discover
connected to: mongod1.realm99.10gen.me
insert query update delete getmore command vsize res faults netIn netOut conn repl time
mongod1.realm99.10gen.me 0 1 0 0 0 1 279m 11m 0 109b 1k 2 RTR 14:38:03
Wed May 15 14:38:03.370 Assertion: 13111:field not found, expected type 2
Wed May 15 14:38:03.370 Assertion: 13111:field not found, expected type 2
0xc1ba860xc1ba86 0xbe35d90xbe35d9 0xbe36fc0xbe36fc 0x7075d9 0x70c684 0x701add 0xc55a0c 0x7f720c86cc6b 0x7f720b5e95ed0x7075d9
0x70c684 0x701add 0xc55a0c 0x7f720c86cc6b 0x7f720b5e95ed
Wed May 15 14:38:03.372 Assertion: 13111:field not found, expected type 2
0xc1ba86 0xbe35d9 0xbe36fc 0x7075d9 0x70c684 0x701add 0xc55a0c 0x7f720c86cc6b 0x7f720b5e95ed
Wed May 15 14:38:03.372 Assertion: 13111:field not found, expected type 2
0xc1ba86 0xbe35d9 0xbe36fc 0x7075d9 0x70c684 0x701add 0xc55a0c 0x7f720c86cc6b 0x7f720b5e95ed
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo15printStackTraceERSo+0x26) [0xc1ba86]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo11msgassertedEiPKc+0xa9) [0xbe35d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xbe36fc]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZNK5mongo11BSONElement6StringEv+0x129) [0x7075d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo4Stat12serverThreadEN5boost10shared_ptrINS0_11ServerStateEEEi+0x7a4) [0x70c684]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvPFvNS_10shared_ptrIN5mongo4Stat11ServerStateEEEiENS2_5list2INS2_5valueIS8_EENSC_IiEEEEEEE3runEv+0x3d) [0x701add]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xc55a0c]
/lib64/libpthread.so.0(+0x7c6b) [0x7f720c86cc6b]
/lib64/libc.so.6(clone+0x6d) [0x7f720b5e95ed]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo15printStackTraceERSo+0x26) [0xc1ba86]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo11msgassertedEiPKc+0xa9) [0xbe35d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xbe36fc]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZNK5mongo11BSONElement6StringEv+0x129) [0x7075d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo4Stat12serverThreadEN5boost10shared_ptrINS0_11ServerStateEEEi+0x7a4) [0x70c684]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvPFvNS_10shared_ptrIN5mongo4Stat11ServerStateEEEiENS2_5list2INS2_5valueIS8_EENSC_IiEEEEEEE3runEv+0x3d) [0x701add]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xc55a0c]
/lib64/libpthread.so.0(+0x7c6b) [0x7f720c86cc6b]
/lib64/libc.so.6(clone+0x6d) [0x7f720b5e95ed]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo15printStackTraceERSo+0x26) [0xc1ba86]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo11msgassertedEiPKc+0xa9) [0xbe35d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xbe36fc]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZNK5mongo11BSONElement6StringEv+0x129) [0x7075d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo4Stat12serverThreadEN5boost10shared_ptrINS0_11ServerStateEEEi+0x7a4) [0x70c684]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvPFvNS_10shared_ptrIN5mongo4Stat11ServerStateEEEiENS2_5list2INS2_5valueIS8_EENSC_IiEEEEEEE3runEv+0x3d) [0x701add]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xc55a0c]
/lib64/libpthread.so.0(+0x7c6b) [0x7f720c86cc6b]
/lib64/libc.so.6(clone+0x6d) [0x7f720b5e95ed]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo15printStackTraceERSo+0x26) [0xc1ba86]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo11msgassertedEiPKc+0xa9) [0xbe35d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xbe36fc]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZNK5mongo11BSONElement6StringEv+0x129) [0x7075d9]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5mongo4Stat12serverThreadEN5boost10shared_ptrINS0_11ServerStateEEEi+0x7a4) [0x70c684]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvPFvNS_10shared_ptrIN5mongo4Stat11ServerStateEEEiENS2_5list2INS2_5valueIS8_EENSC_IiEEEEEEE3runEv+0x3d) [0x701add]
./mongodb-linux-x86_64-subscription-rhel62-v2.4-2013-05-06/bin/mongostat() [0xc55a0c]
/lib64/libpthread.so.0(+0x7c6b) [0x7f720c86cc6b]
/lib64/libc.so.6(clone+0x6d) [0x7f720b5e95ed]