Sharded replicated environment.
mongostat --version says 2.4.6

I'm specifying a host and port, but not providing user and pass despite needing to do so. Instead of saying, 'not authorized', I get a traceback.

TB is as follows (hostnames changed to protect the innocent):

command line:
mongostat --host boxname1 --port 40103 --discover

connected to: boxname1:40103
Wed Sep 25 09:01:00.995 Assertion: 13111:field not found, expected type 2
0xddfb01 0xda2a5b 0xda2f9c 0x6d48d6 0x6dbd54 0x6cf386 0xe285e9 0x3d32a07851 0x3d322e890d
mongostat(_ZN5mongo15printStackTraceERSo+0x21) [0xddfb01]
mongostat(_ZN5mongo11msgassertedEiPKc+0x9b) [0xda2a5b]
mongostat() [0xda2f9c]
mongostat(_ZNK5mongo11BSONElement6StringEv+0x1c6) [0x6d48d6]
mongostat(_ZN5mongo4Stat12serverThreadEN5boost10shared_ptrINS0_11ServerStateEEEi+0x5f4) [0x6dbd54]
mongostat(_ZN5boost6detail11thread_dataINS_3_bi6bind_tIvPFvNS_10shared_ptrIN5mongo4Stat11ServerStateEEEiENS2_5list2INS2_5valueIS8_EENSC_IiEEEEEEE3runEv+0x46) [0x6cf386]
mongostat() [0xe285e9]
/lib64/libpthread.so.0() [0x3d32a07851]
/lib64/libc.so.6(clone+0x6d) [0x3d322e890d]